共查询到20条相似文献,搜索用时 31 毫秒
1.
G. Renault B. S. Nielsen J. Westergaard J. J. Gaardhoje 《Czechoslovak Journal of Physics》2005,55(12):1671-1674
A Large Ion Collider Experiment (ALICE) is the only experiment at the Large Hadron Collider (LHC) dedicated to the study of
heavy ion collisions. The Time Projection Chamber (TPC) is the main tracking detector covering the pseudo rapidity range |η|
< 0.9. It is designed for a maximum multiplicity dN/dy = 8000. The aim of the laser system is to simulate ionizing tracks at predifined positions throughout the drift volume in
order to monitor the TPC response to a known source. In particular, the alignment of the read-out chambers will be performed,
and variations of the drift velocity due to drift field imperfections can be measured and used as calibration data in the
physics data analysis. In this paper we present the design of the pulsed UV laser and optical system, together with the control
and monitoring systems.
for the ALICE Collaboration
Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”,
Budapest, Hungary, 4–9 August 2005. 相似文献
2.
D. Elia G. E. Bruno M. Caselle R. A. Fini V. Lenti V. Manzari V. Paticchio R. Santoro G. Anelli M. Burns I. A. Cali M. Campbell S. Ceresa P. Chochula J. Conrad S. Kapusta A. Kluge M. Morel P. Nilsson F. Osmic P. Riedler G. Stefanini C. Torcato de Matos F. Antinori R. Dima D. Fabris M. Lunardon S. Moretto A. Pepato F. Scarlassara G. Segato R. Turrisi G. Viesti A. Badalà F. Librizzi G. S. Pappalardo A. Pulvirenti F. Riggi M. Cinausero E. Fioretto G. Prete L. Vannucci M. Krivda L. Sándor F. Soramel T. Virgili 《Czechoslovak Journal of Physics》2005,55(12):1635-1638
The silicon pixel detector (SPD) comprises the two innermost layers of the inner tracking system oft he ALICE experiment at
LHC. Prototype SPD assemblies have been tested in high-energy proton and pion beams at the CERN SPS. The method used for data
analysis and the most relevant results in relation to detector performance are presented.
Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”,
Budapest, Hungary, 4–9 August 2005.
On behalf of the Silicon Pixel Detector project in the ALICE Collaboration 相似文献
3.
Kenneth N. Barish 《Czechoslovak Journal of Physics》2005,55(12):1627-1630
The forward spectrometer upgrade of the PHENIX detector aims to add capabilities at forward rapidities to: probe nucleon structure
through W production and promptphotons in polarized p + p, study nucleon structure in nuclei at high parton densities in p
+ A collisions through the measurement of γ and π0 in the forward region, greatly extend the acceptance for high p
T γ-jet measurements (jet tomography) in A + A, and increase our capabilities to measure the production quarkonium states by
giving sensitivity to the χ
c
through the J/ψ + γ channel.
for the PHENIX Forward Upgrade Collaboration
Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”,
Budapest, Hungary, 4–9 August 2005. 相似文献
4.
M. Estienne 《Physics of Atomic Nuclei》2008,71(9):1535-1542
The observation of the strong suppression of high-p
t hadrons in heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) at BNL has motivated a large experimental program
using hard probes to characterize the deconfined medium created. However, what can be denoted as “leading particle” physics
accessible at RHIC presents some limitations which motivate at higher energy the study of much more penetrating objects: jets.
The gain in center-of-mass energy expected at the Large Hadron Collider (LHC) at CERN will definitively improve our understanding
on how the energy is lost in the system, opening a major new window of study: the physics of jets on an event-by-event basis.
We will concentrate on the expected performance for jet reconstruction in ALICE using the EMCal calorimeter.
(for the ALICE Collaboration)
The text was submitted by the author in English. 相似文献
5.
We analyse, within the “flavoured” leptogenesis scenario of baryon asymmetry generation, the interplay of “low energy” CP-violation,
originating from the PMNS neutrino mixing matrix U, and “high energy” CP-violation, which can be present in the matrix of neutrino Yukawa couplings, λ, and can manifest itself only in “high” energy scale processes. The type I see-saw model with three heavy right-handed Majorana
neutrinos having a hierarchical spectrum is considered. The “orthogonal” parameterisation of the matrix of neutrino Yukawa
couplings, which involves a complex orthogonal matrix R, is employed. In this approach the matrix R is the source of “high energy” CP-violation. Results for normal hierarchical (NH) and inverted hierarchical (IH) light neutrino
mass spectrum are derived in the case of decoupling of the heaviest right-handed Majorana neutrino. It is shown that taking
into account the contribution to Y
B
due to the CP-violating phases in the neutrino mixing matrix U can change drastically the predictions for Y
B
, obtained assuming that only “high energy” CP-violation from the R-matrix is operative in leptogenesis. In the case of the IH spectrum, in particular, there exist significant regions in the
corresponding parameter space where the purely “high energy” contribution in Y
B
plays a subdominant role in the production of baryon asymmetry compatible with the observations.
Also at Institute of Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria. 相似文献
6.
G. A. Kozlov 《Physics of Particles and Nuclei》2010,41(6):954-956
A field model for a quark and an antiquark binding is described. Quarks interact via a gauge unparticle (“ungluon”). The model
is formulated in terms of Lagrangian which features the source field S(x) which becomes a local pseudo-Goldstone field of conformal symmetry — the pseudodilaton mode and from which the gauge non-primary
unparticle field is derived by B
μ(x) ∼ ∂μ
S(x). Because the conformal sector is strongly coupled, the mode S(x) may be one of new states accessible at high energies. We have carried out an analysis of the important quantity that enters
in the “ungluon” exchange pattern — the “ungluon” propagator. 相似文献
7.
The phase transition “triangular lattice-vortex liquid” in layered high-T
c
superconductors in the presence of pinning centers is studied. A two-dimensional system of vortices simulating the superconducting
layers in a high-T
c
Shubnikov phase is calculated by the Monte Carlo method. It was found that in the presence of defects the melting of the
vortex lattice proceeds in two stages: First, the ideal triangular lattice transforms at low temperature (≃3 K)into islands
which are pinned to the pinning centers and rotate around them and then, at a higher temperature (≃8 K for T
c
584 K), the boundaries of the “islands” become smeared and the system transforms into a vortex liquid. As the pinning force
increases, the temperatures of both phase transitions shift: The temperature of the point “triangular lattice-rotating lattice”
decreases slightly (to ≃2 K)and the temperature of the phase transition “rotating lattice-vortex liquid” increases substantially
(≃70 K).
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 269–274 (25 August 1997) 相似文献
8.
D. Blaschke Yu. L. Kalinovsky A. E. Radzhabov M. K. Volkov 《Physics of Particles and Nuclei Letters》2006,3(5):327-330
The properties and temperature behavior of the π and σ bound states are studied in the framework of the nonlocal model with
a separable interaction kernel, based on the quark Dyson-Schwinger and meson Bethe-Salpeter equations. M
π(T), f
π(T), M
σ(T), and Γσ → ππ(T) are considered above and below the deconfinement and chiral restoration transitions.
Talk at the Round-Table Discussion “Searching for a Mixed Phase of Strongly Interacting Matter at the JINR Nuclotron,” Dubna,
July 7–9, 2005.
The text was submitted by the authors in English. 相似文献
9.
A. Kh. Inoyatov L. L. Perevoshchikov A. Kovalík O. Dragoun D. V. Filosofov 《The European Physical Journal A - Hadrons and Nuclei》2011,47(7):84
The conversion electron spectrum of the 22.5keV M1 + E2 nuclear transition in 149Sm from the electron capture decay of 149Eu was experimentally studied for the “Eu2O3” and “EuF3” compounds in which 149Eu ions have the same assumed oxidation number +3 . While the energies of the L, M, N, O, and P1 conversion lines for “EuF3” were lower, on average, by 1.7(1), 2.7(2), 2.3(3), 4.1(2), and 5.7(9)eV, respectively, than those for “Eu2O3”, no changes between the two ligand complexes were observed for relative intensities of the conversion lines and their natural
widths within the error limits. 相似文献
10.
S. Okuma H. Miyatake N. Nishida Y. Ueda S. Katsuyama K. Kosuge J. H. Brewer 《Hyperfine Interactions》1991,63(1-4):265-270b
Spin-glass like magnetic ordering of iron moments was observed in both orthorhombic and tetragonal YBa2(Cu1−xFex)3Oy (x=0.08) by μ+SR measurements. In a “Tetra” sample, all the muons sense the superconducting transition at 60 K and magnetic ordering at
around 15 K, while in an “Ortho” sample they reveal that two magnetically different parts exist in the sample: about 40% of
the sample is superconducting withT
c
≈90K and the remaining part is magnetic withT
M≈33K. These phenomena can be explained in terms of clustering of the Fe atoms in the “Ortho” sample. 相似文献
11.
M. C. Suarez 《Indian Journal of Physics》2011,85(7):1085-1089
We present an analysis of relative baryon to meson production for intermediate transverse momentum hadrons associated with
a high-p
T
trigger. The results of pion and (anti)proton spectra and ratios are presented for the “jet” and “ridge” components of the
two-dimensional Δν − Δϕ triggered correlations in central Au+Au collisions at ?{sNN }\sqrt {s_{NN} } = 200 GeV. We compare these results with the inclusive (non-triggered) measurements for the same data, and discuss our observations
in conjunction with the results from d+Au, and pp data. 相似文献
12.
Shaolin Liao Ronald J. Vernon 《International Journal of Infrared and Millimeter Waves》2007,28(6):479-490
The newly developed Taylor-Interpolation-FFT (TI-FFT) algorithm dramatically increases the computational speeds for millimeter
wave propagation from a planar (cylindrical) surface onto a “quasi-planar” (“quasi-cylindrical”) surface. Two different scenarios
are considered in this article: the planar TI-FFT is for the computation of the wave propagation from a plane onto a “quasi-planar” surface and the cylindrical TI-FFT is for the computation of wave propagation from a cylindrical surface onto a “quasi-cylindrical” surface. Due to the
use of the FFT, the TI-FFT algorithm has a computational complexity of O(N
2 log2
N
2) for an N × N computational grid, instead of N
4 for the direct integration method. The TI-FFT algorithm has a low sampling rate according to the Nyquist sampling theorem.
The algorithm has accuracy down to −80 dB and it works particularly well for narrow-band fields and “quasi-planar” (“quasi-cylindrical”)
surfaces. 相似文献
13.
M. V. Tokarev I. Zborovský A. Kechechyan A. Alakhverdyants 《Physics of Particles and Nuclei Letters》2011,8(6):533-541
The general concepts in the critical phenomena related with the notions of “scaling” and “universality” are considered. Behavior
of various systems near a phase transition is displayed. Search for clear signatures of the phase transition of the nuclear
matter and location of the critical point in heavy-ion collisions (HIC) is discussed. The experimental data on inclusive spectra measured in HIC at RHIC and SPS over a wide range of energies s
N N
1/2 = 9–200 GeV are analyzed in the framework of z-scaling. A microscopic scenario of the constituent interactions is presented. Dependence of the energy loss on the momentum
of the produced hadron, energy and centrality of the collision is studied. Self-similarity of the constituent interactions
described in terms of momentum fractions is used to characterize the nuclear medium by “specific heat” and colliding nuclei
by fractal dimensions. Preferable kinematical regions to search for signatures of the phase transition of the nuclear matter
produced in HIC are discussed. Discontinuity of the “specific heat” is assumed to be a signature of the phase transition and the critical
point. 相似文献
14.
For stationary cylindrically symmetric solutions of the Einstein-Maxwell equation we have shown that the “charged” solutions
of McCrea, Chitre et al. (CGN), Van den Bergh and Wils (VW) can be obtained from the seed metrics using generating conjecture.
The McCrea “charged” solution has as a seed vacuum metric the Van Stockum solution with a Killing vector (0, 0, 1, 0). The
CGN “charged” solution and the VW “charged” solution have the static seed metrics connected by the complex substitutiont → iz, z → it and the Killing vector which is a simple linear combination of∂
ϕ
and∂
t
Killing vectors (VW), respectively∂
ϕ
and∂
z
Killing vectors (CGN). 相似文献
15.
Antonino Marciano 《Czechoslovak Journal of Physics》2005,55(11):1479-1485
I summarize results recently obtained in collaboration with Amelino-Camelia, Bruno and Mandanici (preprint University of Rome
“La Sapienza”, August, 2005) that concern an analysis of the path of a massless particle in a q-de Sitter space-time and an approximation scheme suitable for the corresponding analysis in a quantum FRW Universe. On the
basis of some arguments in the quantum-gravity literature, the q deformation parameter is assumed to depend on both the Planck scale and the curvature, leading to results that are significantly
different from those of other studies of Planck-scale effects in cosmology, where the possibility of an interplay between
curvature and Planck scale was ignored.
Presented at the International Colloquium “Integrable Systems and Quantum Symmetries”, Prague, 16–18 June 2005. 相似文献
16.
M. A. Korzhuev 《JETP Letters》1996,64(2):105-109
The reasons for the anomalously rapid (for solids) growth of “cancers” (filamentary crystals, hills, pores, and other formations)
on the surface of samples of superionic conductors with mixed electronic-ionic conductivity (of the type Cu2−x
Se and Ag2Te) are discussed. The effects are attributed to the acceleration of mobile ions and activated ions in the “core” of the superionic
by free electrons in the joint “chemical” diffusion of ions and electrons in the samples.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 2, 97–100 (25 July 1996) 相似文献
17.
A two-photon impurity absorption coefficient of the “quantum dot — D(−)-center” complexes synthesized in a transparent dielectric matrix is calculated within the model of zero-radius potential.
The evolution of spectral dependence of the absorption coefficient of the nanoheterostructure based on semiconductor CdS
x
Se
1−x
glasses is studied versus the average quantum-dot radius. It is shown that the contribution of the two-photon impurity absorption
to the exited two-photon luminescence is fairly significant at a reasonable quantum-dot concentration.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 46–50, July, 2005. 相似文献
18.
N. A. Babushkina A. N. Taldenkov A. V. Kalinov L. M. Fisher O. Yu. Gorbenko J. Rohrkamp T. Lorenz D. I. Khomskii K. I. Kugel 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(10):1345-1347
The oxygen isotope effect was investigated in cobalt oxides (Pr1 − y
Eu
y
)0.7Ca0.3CoO3 (0.12 < y < 0.26). The measurements of magnetization, electric resistivity, differential magnetic susceptibility, thermal expansion,
and specific heat show that as the Eu concentration increases, a transition from “ferromagnetic metal” to “weakly magnetic
insulator” is observed at y ≈ 0.18. In the insulating ground state, the transition occurs with a Co spin-state change that is suppressed in the ferromagnetic
(FM) metallic phase. The spin-state transition at y > 0.18 is accompanied by a substantial oxygen isotope effect that is virtually absent in the FM phase (y < 0.18). 相似文献
19.
Giant magnetoresistance in Hg
1−x−y
Mn
x
Fe
y
Te crystals is caused by clusters with “antiferromagnetic” (Mn-Te-Mn-Te, Mn-Te-Fe-Te) and “ferromagnetic” (Fe-Fe-Fe) ordering. The effect is due to the fact that the charge carriers taking part in electric current interact with the “ferromagnetic”
cluster subsystem (Fe-Fe-Fe) magnetized to saturation and become spin-polarized. These spin-polarized charge carriers are strongly scattered by the “antiferromagnetic”
Mn-Te-Mn-Te and Mn-Te-Fe-Te clusters, because the magnetic moments inside the clusters and resultant moments of clusters have chaotic orientations. Investigations
of kinetic coefficients of Hg
1−x−y
Mn
x
Fe
y
Te crystals before and after thermal treatment show that there is no marked correlation between the giant magnetoresistance
and charge-carrier concentration, mobility, and band parameters of crystals.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 28–33, October, 2007. 相似文献
20.
We use the decomposition of o(3, 1) = sl(2; ℂ)1 ⊕sl(2; ℂ)2 in order to describe nonstandard quantum deformation of o(3, 1) linked with Jordanian deformation of sl(2; ℂ). Using the
twist quantization technique, we obtain the deformed coproducts and antipodes, which can be expressed in terms of real physical
Lorentz generators. We describe the extension of the considered deformation of D = 4 Lorentz algebra to the twist deformation of D = 4 Poincare algebra with dimensionless deformation parameter.
Presented at the International Colloquium “Integrable Systems and Quantum Symmetries”, Prague, 16–18 June 2005. 相似文献