We study a two-species totally asymmetric exclusion process (TASEP) in 1D lattice in which the particles of both species move stochastically in opposite directions (with rate
v
) and switch ...directions stochastically (with rate
α
) while adjacent a particle of either species. We focus on the cluster size distribution
P
(
m
), where a cluster is taken to be a contiguous set of sites occupied by either species, as a function of
Q
=
v
/
α
. For a total density
ρ
of particles, in the limit
Q
→
0
, the cluster size distribution is shown to be
P
(
m
)
=
1
/
ρ
-
1
e
-
m
/
ln
ρ
and the mean cluster size
⟨
m
⟩
=
1
/
(
1
-
ρ
)
, results which are independent of
Q
and are identical to those for the simple exclusion process. By contrast, in the opposite limit,
Q
≫
1
, we find the average cluster size,
⟨
m
⟩
∝
Q
1
/
2
—similar to the that for the persistent exclusion process (PEP), although the cluster size distributions are different in both limits. We further find that, for a finite system with
L
sites, the probability distribution of cluster sizes exhibits a distinct peak which corresponds to the formation of a single cluster of size
m
s
=
ρ
L
. However, this peak vanishes in the thermodynamic limit
L
→
∞
. Interestingly, the probability of this largest size cluster,
P
(
m
s
)
, for different
L
,
ρ
and
Q
exhibits data collapse in terms of the scaled variable
Q
s
≡
Q
/
L
2
ρ
(
1
-
ρ
)
. The statistical features of the clustering observed for this minimal model may be relevant for
active
particle systems in 1D.
Performance of a new LMRPC prototype for the STAR MTD system Wang, Y.; Chen, H.S.; Ding, W.C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2011, Letnik:
640, Številka:
1
Journal Article
Recenzirano
A new prototype of a Long-Strip Multi-Gap Resistive Plate Chamber (LMRPC) for the STAR Muon Telescope Detector (MTD) at RHIC has been developed. This prototype has an active area of 52×90
cm
2 and ...consists of six 250
μm wide gaps. Each detector has 12 strips, read-out at both ends, which are each 3.8
cm wide and 90
cm long with 0.6
cm intervals. In cosmic-ray tests, the efficiency was larger than 95% and the time resolution was ∼75
ps for the 94% Freon, 5% iso-butane, and 1% SF
6 gas mixture. There was good uniformity in the performance across the different strips. The module was also tested in a proton beam at IHEP in Beijing. The efficiency was close to 100% and the best timing resolution achieved was 55
ps for the 90% Freon, 5% iso-butane, and 5% SF
6 gas mixture. Trigger scans along and across the strip direction were also performed.
In this Letter, comprehensive results on π±, K±, KS0, p(p¯) and Λ(Λ¯) production at mid-rapidity (0<yCMS<0.5) in p–Pb collisions at sNN=5.02 TeV, measured by the ALICE detector at the LHC, are ...reported. The transverse momentum distributions exhibit a hardening as a function of event multiplicity, which is stronger for heavier particles. This behavior is similar to what has been observed in pp and Pb–Pb collisions at the LHC. The measured pT distributions are compared to d–Au, Au–Au and Pb–Pb results at lower energy and with predictions based on QCD-inspired and hydrodynamic models.
The elliptic, v2, triangular, v3, and quadrangular, v4, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions, and (anti-)protons in Pb–Pb collisions at ...sNN=2.76 TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range |η|<0.8 at different collision centralities and as a function of transverse momentum, pT, out to pT=20 GeV/c. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for pT>8 GeV/c. The small pT dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to pT=8 GeV/c. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least pT=8 GeV/c indicating that the particle type dependence persists out to high pT.
The production of Ξ− and Ω− baryons and their anti-particles in Pb–Pb collisions at sNN=2.76 TeV has been measured using the ALICE detector. The transverse momentum spectra at mid-rapidity (|y|<0.5) ...for charged Ξ and Ω hyperons have been studied in the range 0.6<pT<8.0 GeV/c and 1.2<pT<7.0 GeV/c, respectively, and in several centrality intervals (from the most central 0–10% to the most peripheral 60–80% collisions). These spectra have been compared with the predictions of recent hydrodynamic models. In particular, the Kraków and EPOS models give a satisfactory description of the data, with the latter covering a wider pT range. Mid-rapidity yields, integrated over pT, have been determined. The hyperon-to-pion ratios are similar to those at RHIC: they rise smoothly with centrality up to 〈Npart〉∼150 and saturate thereafter. The enhancements (yields per participant nucleon relative to those in pp collisions) increase both with the strangeness content of the baryon and with centrality, but are less pronounced than at lower energies.
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