Hadronic resonances are used to probe the hadron gas produced in the late stage of heavy-ion collisions since they decay on the same timescale, of the order of 1–10 fm/
c
, as the decoupling time of ...the system. In the hadron gas, (pseudo)elastic scatterings among the products of resonances that decayed before the kinetic freeze-out and regeneration processes counteract each other, the net effect depending on the resonance lifetime, the duration of the hadronic phase, and the hadronic cross sections at play. In this context, the
Σ
(
1385
)
±
particle is of particular interest as models predict that regeneration dominates over rescattering despite its relatively short lifetime of about 5.5 fm/
c
. The first measurement of the
Σ
(
1385
)
±
resonance production at midrapidity in Pb–Pb collisions at
s
NN
=
5.02
TeV with the ALICE detector is presented in this Letter. The resonances are reconstructed via their hadronic decay channel,
Λ
π
, as a function of the transverse momentum (
p
T
) and the collision centrality. The results are discussed in comparison with the measured yield of pions and with expectations from the statistical hadronization model as well as commonly employed event generators, including PYTHIA8/Angantyr and EPOS3 coupled to the UrQMD hadronic cascade afterburner. None of the models can describe the data. For
Σ
(
1385
)
±
, a similar behaviour as
K
∗
(
892
)
0
is observed in data unlike the predictions of EPOS3 with afterburner.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A newly developed observable for correlations between symmetry planes, which characterize the direction of the anisotropic emission of produced particles, is measured in Pb–Pb collisions at
s
NN
... = 2.76 TeV with ALICE. This so-called Gaussian Estimator allows for the first time the study of these quantities without the influence of correlations between different flow amplitudes. The centrality dependence of various correlations between two, three and four symmetry planes is presented. The ordering of magnitude between these symmetry plane correlations is discussed and the results of the Gaussian Estimator are compared with measurements of previously used estimators. The results utilizing the new estimator lead to significantly smaller correlations than reported by studies using the Scalar Product method. Furthermore, the obtained symmetry plane correlations are compared to state-of-the-art hydrodynamic model calculations for the evolution of heavy-ion collisions. While the model predictions provide a qualitative description of the data, quantitative agreement is not always observed, particularly for correlators with significant non-linear response of the medium to initial state anisotropies of the collision system. As these results provide unique and independent information, their usage in future Bayesian analysis can further constrain our knowledge on the properties of the QCD matter produced in ultrarelativistic heavy-ion collisions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A study of multiplicity and pseudorapidity distributions of inclusive photons measured in pp and p–Pb collisions at a center-of-mass energy per nucleon–nucleon collision of
s
NN
=
5.02
TeV using the ...ALICE detector in the forward pseudorapidity region 2.3
<
η
lab
<
3.9 is presented. Measurements in p–Pb collisions are reported for two beam configurations in which the directions of the proton and lead ion beam were reversed. The pseudorapidity distributions in p–Pb collisions are obtained for seven centrality classes which are defined based on different event activity estimators, i.e., the charged-particle multiplicity measured at midrapidity as well as the energy deposited in a calorimeter at beam rapidity. The inclusive photon multiplicity distributions for both pp and p–Pb collisions are described by double negative binomial distributions. The pseudorapidity distributions of inclusive photons are compared to those of charged particles at midrapidity in pp collisions and for different centrality classes in p–Pb collisions. The results are compared to predictions from various Monte Carlo event generators. None of the generators considered in this paper reproduces the inclusive photon multiplicity distributions in the reported multiplicity range. The pseudorapidity distributions are, however, better described by the same generators.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The production of the
Λ
(1520) baryonic resonance has been measured at midrapidity in inelastic pp collisions at
s
=
7
TeV
and in p–Pb collisions at
s
NN
=
5.02
TeV
for non-single diffractive events ...and in multiplicity classes. The resonance is reconstructed through its hadronic decay channel
Λ
(1520)
→
pK
-
and the charge conjugate with the ALICE detector. The integrated yields and mean transverse momenta are calculated from the measured transverse momentum distributions in pp and p–Pb collisions. The mean transverse momenta follow mass ordering as previously observed for other hyperons in the same collision systems. A Blast-Wave function constrained by other light hadrons (
π
, K,
K
S
0
, p,
Λ
) describes the shape of the
Λ
(1520) transverse momentum distribution up to
3.5
GeV
/
c
in p–Pb collisions. In the framework of this model, this observation suggests that the
Λ
(1520) resonance participates in the same collective radial flow as other light hadrons. The ratio of the yield of
Λ
(
1520
)
to the yield of the ground state particle
Λ
remains constant as a function of charged-particle multiplicity, suggesting that there is no net effect of the hadronic phase in p–Pb collisions on the
Λ
(1520) yield.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Two-particle correlations with
K
S
0
,
Λ
/
Λ
¯
, and charged hadrons as trigger particles in the transverse momentum range
8
<
p
T
,
trig
<
16
GeV/
c
, and associated charged particles within
1
<
p
...T
,
assoc
<
8
GeV/
c
, are studied at midrapidity in pp and central Pb–Pb collisions at a centre-of-mass energy per nucleon–nucleon collision
s
NN
=
5.02
TeV with the ALICE detector at the LHC. After subtracting the contributions of the flow background, the per-trigger yields are extracted on both the near and away sides, and the ratio in Pb–Pb collisions with respect to pp collisions (
I
AA
) is computed. The per-trigger yield in Pb–Pb collisions on the away side is strongly suppressed to the level of
I
AA
≈
0.6
for
p
T
,
assoc
>
3
GeV/
c
as expected from strong in-medium energy loss, while an enhancement develops at low
p
T
,
assoc
on both the near and away sides, reaching
I
AA
≈
1.8
and 2.7 respectively. These findings are in good agreement with previous ALICE measurements from two-particle correlations triggered by neutral pions (
π
0
–h) and charged hadrons (h–h) in Pb–Pb collisions at
s
NN
=
2.76
TeV. Moreover, the correlations with
K
S
0
mesons and
Λ
/
Λ
¯
baryons as trigger particles are compared to those of inclusive charged hadrons. The results are compared with the predictions of Monte Carlo models.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
The
p
T
-differential non-linear flow modes,
v
4
,
22
,
v
5
,
32
,
v
6
,
33
and
v
6
,
222
for
π
±
, K
±
,
K
S
0
, p +
p
¯
, Λ +
Λ
¯
and
ϕ
-meson have been measured for the first time at
s
...NN
= 5
.
02 TeV in Pb-Pb collisions with the ALICE detector at the Large Hadron Collider. The results were obtained with a multi-particle technique, correlating the identified hadrons with reference charged particles from a different pseudorapidity region. These non-linear observables probe the contribution from the second and third order initial spatial anisotropy coefficients to higher flow harmonics. All the characteristic features observed in previous
p
T
-differential anisotropic flow measurements for various particle species are also present in the non-linear flow modes, i.e. increase of magnitude with increasing centrality percentile, mass ordering at low
p
T
and particle type grouping in the intermediate
p
T
range. Hydrodynamical calculations (iEBE-VISHNU) that use different initial conditions and values of shear and bulk viscosity to entropy density ratios are confronted with the data at low transverse momenta. These calculations exhibit a better agreement with the anisotropic flow coefficients than the non-linear flow modes. These observations indicate that non-linear flow modes can provide additional discriminatory power in the study of initial conditions as well as new stringent constraints to hydrodynamical calculations.
A series of archaeological features has been studied by means of the scanning electronic microscopy. It was shown that due to the oxidation process, the surface layer is enriched with some elements, ...which were present at unaltered metal (Ag, Pb) and those included later (As, Zn, Pb). It imposes meaningful limitation for use of the X-ray fluorescence and spectral analysis, which allow obtaining only total (patina + metal) composition. Sixteen minerals (oxides, carbonates, sulphates, chlorides, phosphates, sulfides and native phases) are established in patina composition. Tin bronze structure contains the impurities, which may be an evidence of import to Perm Region of tin and silver possibly from Altai, tin and lead possibly from Karelia during "harinsky" and "rodanovsky" cultures respectively. Various composition of the alloys used for casting and filigree witnesses that ancient metallurgists had known about alloys handling. The presence of barium and fluorine can tell us about composition of the used furnacecharge. The obtained data may be the basis for chemical-metallurgical typification of pieces from nonferrous (and noble) metals.
4-Methylene-4
H
-pyrans are popular merocyanine dyes, but their functionalization is limited by the Knoevenagel condensation with aromatic aldehydes. In this work, we developed a novel approach for ...the construction of a new class of pyran fluorophores based on enamination and subsequent nucleophilic substitution of the dimethylamino group
via
1,8-conjugate addition/elimination. This methodology includes selective transformations leading to previously unknown symmetrical and asymmetrical structures. The dimethylaminovinyl-substituted pyrans are reactive intermediates and can be considered as a convenient synthetic tool for the construction of new merocyanines with tunable fluorescence (417-628 nm). The main strategies for the modification of the pyran moiety have been determined for the construction and targeted design of fluorophores. Pyrans bearing two enamine moieties demonstrate significant light extinction coefficients (up to 116 000 M
−1
cm
−1
), high quantum yields (up to 69%) and large Stokes shifts (up to 152 nm) because of their strong push-pull nature. Density Functional Theory (DFT) calculations were performed for the explanation of the structural and photophysical features of the prepared merocyanines. The developed approach can be considered as a useful platform for further application of 4-methylene-4
H
-pyrans as promising fluorophores for sensors and solar cells, and in bioimaging.
A novel approach for the construction of a new class of pyran fluorophores has been developed based on enamination and subsequent nucleophilic substitution of the dimethylamino group
via
1,8-conjugate addition/elimination.
A
bstract
The production of prompt D
0
, D
+
, and D
*+
mesons was measured at midrapidity (|
y
|
<
0.5) in Pb–Pb collisions at the centre-of-mass energy per nucleon–nucleon pair
s
NN
= 5
.
02 TeV ...with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decay channels and their production yields were measured in central (0–10%) and semicentral (30–50%) collisions. The measurement was performed up to a transverse momentum (
p
T
) of 36 or 50 GeV/c depending on the D meson species and the centrality interval. For the first time in Pb–Pb collisions at the LHC, the yield of D
0
mesons was measured down to
p
T
= 0, which allowed a model-independent determination of the
p
T
-integrated yield per unit of rapidity (d
N/
d
y
). A maximum suppression by a factor 5 and 2.5 was observed with the nuclear modification factor (
R
AA
) of prompt D mesons at
p
T
= 6–8 GeV/c for the 0–10% and 30–50% centrality classes, respectively. The D-meson
R
AA is compared with that of charged pions, charged hadrons, and J
/ψ
mesons as well as with theoretical predictions. The analysis of the agreement between the measured
R
AA
, elliptic (
v
2
) and triangular (
v
3
) flow, and the model predictions allowed us to constrain the charm spatial diffusion coefficient
D
s
. Furthermore the comparison of
R
AA
and
v
2
with different implementations of the same models provides an important insight into the role of radiative energy loss as well as charm quark recombination in the hadronisation mechanisms.
PDF
