This paper presents the test results of the second prototype of SAMPA, the ASIC designed for the upgrade of read-out front end electronics of the ALICE Time Projection Chamber (TPC) and Muon Chamber ...(MCH). SAMPA is made in a 130 nm CMOS technology with 1.25 V nominal voltage supply and provides 32 channels, with selectable input polarity, and three possible combinations of shaping time and sensitivity. Each channel consists of a Charge Sensitive Amplifier, a semi-Gaussian shaper and a 10-bit ADC; a Digital Signal Processor provides digital filtering and compression capability. In the second prototype run both full chip and single test blocks were fabricated, allowing block characterization and full system behaviour studies. Experimental results are here presented showing agreement with requirements for both the blocks and the full chip.
The accumulation of three major carotenoid derivatives-crocetin glycosides, picrocrocin, and safranal-is in large part responsible for the color, bitter taste, and aroma of saffron, which is obtained ...from the dried styles of Crocus. We have identified and functionally characterized the Crocus zeaxanthin 7,8(7′,8′)-cleavage dioxygenase gene (CsZCD), which codes for a chromoplast enzyme that initiates the biogenesis of these derivatives. The Crocus carotenoid 9,10(9′,10′)-cleavage dioxygenase gene (CsCCD) also has been cloned, and the comparison of substrate specificities between these two enzymes has shown that the CsCCD enzyme acts on a broader range of precursors. CsZCD expression is restricted to the style branch tissues and is enhanced under dehydration stress, whereas CsCCD is expressed constitutively in flower and leaf tissues irrespective of dehydration stress. Electron microscopy revealed that the accumulation of saffron metabolites is accompanied by the differentiation of amyloplasts and chromoplasts and by interactions between chromoplasts and the vacuole. Our data suggest that a stepwise sequence exists that involves the oxidative cleavage of zeaxanthin in chromoplasts followed by the sequestration of modified water-soluble derivatives into the central vacuole.
A
bstract
The production of prompt charmed mesons D
0
, D
+
and D
∗+
, and their antiparticles, was measured with the ALICE detector in Pb-Pb collisions at the centre-of-mass energy per nucleon pair,
...s
N
N
, of 2
.
76 TeV. The production yields for rapidity |
y
|
<
0
.
5 are presented as a function of transverse momentum,
p
T
, in the interval 1–36 GeV
/c
for the centrality class 0–10% and in the interval 1–16 GeV
/c
for the centrality class 30–50%. The nuclear modification factor
R
AA
was computed using a proton-proton reference at
s
=
2.76
TeV, based on measurements at
s
=
7
TeV and on theoretical calculations. A maximum suppression by a factor of 5-6 with respect to binary-scaled pp yields is observed for the most central collisions at
p
T
of about 10 GeV
/c
. A suppression by a factor of about 2-3 persists at the highest
p
T
covered by the measurements. At low
p
T
(1-3 GeV
/c
), the
R
AA
has large uncertainties that span the range 0.35 (factor of about 3 suppression) to 1 (no suppression). In all
p
T
intervals, the
R
AA
is larger in the 30-50% centrality class compared to central collisions. The D-meson
R
AA
is also compared with that of charged pions and, at large
p
T
, charged hadrons, and with model calculations.
Like seed plants, liverworts synthesize and accumulate a myriad of isoprenoid compounds. Using antibodies raised against several isoprenoid biosynthetic enzymes, we investigated their intracellular ...compartmentation by in situ immunolocalization from Marchantia polymorpha. The enzymes examined were deoxy-xylulose phosphate synthase, geranyl diphosphate synthase, farnesyl diphosphate synthase, geranylgeranyl diphosphate synthase, monoterpene synthase, geranylgeranyl diphosphate reductase, phytoene synthase, and phytoene desaturase. Our results show that liverwort oil bodies, which are organelles bound by a single unit membrane, possess isoprenoid biosynthetic enzymes similar to those found in plastids and the cytosol. We postulate that oil bodies play a dynamic role in cell metabolism in addition to their role as sites of essential oil accumulation and sequestration. The occurrence of such enzymes in different cellular compartments might be due to multiple targeting of gene products to various organelles.
ALICE is an LHC experiment devoted to the study of strongly interacting matter in proton--proton, proton--nucleus and nucleus--nucleus collisions at ultra-relativistic energies. The ALICE VZERO ...system, made of two scintillator arrays at asymmetric positions, one on each side of the interaction point, plays a central role in ALICE. In addition to its core function as a trigger, the VZERO system is used to monitor LHC beam conditions, to reject beam-induced backgrounds and to measure basic physics quantities such as luminosity, particle multiplicity, centrality and event plane direction in nucleus-nucleus collisions. After describing the VZERO system, this publication presents its performance over more than four years of operation at the LHC.
The PHENIX collaboration presents first measurements of low-momentum (0.4<p_{T}<3 GeV/c) direct-photon yields from Au+Au collisions at sqrts_{NN}=39 and 62.4 GeV. For both beam energies the ...direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in Au+Au collisions at sqrts_{NN}=200. Analyzing the photon yield as a function of the experimental observable dN_{ch}/dη reveals that the low-momentum (>1 GeV/c) direct-photon yield dN_{γ}^{dir}/dη is a smooth function of dN_{ch}/dη and can be well described as proportional to (dN_{ch}/dη)^{α} with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high p_{T} (>5 GeV/c), but when results from different collision energies are compared, an additional sqrts_{NN}-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.
A
bstract
Production of inclusive charmonia in pp collisions at center-of-mass energy of
s
= 13 TeV and p–Pb collisions at center-of-mass energy per nucleon pair of
s
NN
= 8
.
16 TeV is studied as a ...function of charged-particle pseudorapidity density with ALICE. Ground and excited charmonium states (
J/ψ
,
ψ
(2S)) are measured from their dimuon decays in the interval of rapidity in the center-of-mass frame 2
.
5
< y
cms
<
4
.
0 for pp collisions, and 2
.
03
< y
cms
<
3
.
53 and −4
.
46
< y
cms
<
−2
.
96 for p–Pb collisions. The charged-particle pseudorapidity density is measured around midrapidity (|
η
|
<
1
.
0). In pp collisions, the measured charged-particle multiplicity extends to about six times the average value, while in p-Pb collisions at forward (backward) rapidity a multiplicity corresponding to about three (four) times the average is reached. The
ψ
(2S) yield increases with the charged-particle pseudorapidity density. The ratio of
ψ
(2S) over
J/ψ
yield does not show a significant multiplicity dependence in either colliding system, suggesting a similar behavior of
J/ψ
and
ψ
(2S) yields with respect to charged-particle pseudorapidity density. Results for the
ψ
(2S) yield and its ratio with respect to
J/ψ
agree with available model calculations.
A bstract The azimuthal anisotropy of particles associated with jets (jet particles) at midrapidity is measured for the first time in p-Pb and Pb-Pb collisions at $$ \sqrt{{\textrm{s}}_{\textrm{NN}}} ...$$ s NN = 5 . 02 TeV down to transverse momentum ( p T ) of 0.5 GeV/ c and 2 GeV/ c , respectively, with ALICE. The results obtained in p-Pb collisions are based on a novel three-particle correlation technique. The azimuthal anisotropy coefficient v 2 in high-multiplicity p-Pb collisions is positive, with a significance reaching 6.8 σ at low p T , and its magnitude is smaller than in semicentral Pb-Pb collisions. In contrast to the measurements in Pb-Pb collisions, the v 2 coefficient is also found independent of p T within uncertainties. Comparisons with the inclusive charged-particle v 2 and with AMPT calculations are discussed. The predictions suggest that parton interactions play an important role in generating a non-zero jet-particle v 2 in p-Pb collisions, even though they overestimate the reported measurement. These observations shed new insights on the understanding of the origin of the collective behaviour of jet particles in small systems such as p-Pb collisions, and provide significant stringent new constraints to models.
A
bstract
The production of strange hadrons (
K
S
0
, Λ, Ξ
±
, and Ω
±
), baryon-to-meson ratios (Λ
/
K
S
0
, Ξ
/
K
S
0
, and Ω
/
K
S
0
), and baryon-to-baryon ratios (Ξ
/
Λ, Ω
/
Λ, and Ω
/
Ξ) ...associated with jets and the underlying event were measured as a function of transverse momentum (
p
T
) in pp collisions at
s
= 13 TeV and p Pb collisions at
s
NN
= 5
.
02 TeV with the ALICE detector at the LHC. The inclusive production of the same particle species and the corresponding ratios are also reported. The production of multi-strange hadrons, Ξ
±
and Ω
±
, and their associated particle ratios in jets and in the underlying event are measured for the first time. In both pp and p–Pb collisions, the baryon-to-meson and baryon-to-baryon yield ratios measured in jets differ from the inclusive particle production for low and intermediate hadron
p
T
(0.6–6 GeV/
c
). Ratios measured in the underlying event are in turn similar to those measured for inclusive particle production. In pp collisions, the particle production in jets is compared with P
ythia
8 predictions with three colour-reconnection implementation modes. None of them fully reproduces the data in the measured hadron
p
T
region. The maximum deviation is observed for Ξ
±
and Ω
±
which reaches a factor of about six. The event multiplicity dependence is further investigated in p−Pb collisions. In contrast to what is observed in the underlying event, there is no significant event-multiplicity dependence for particle production in jets. The presented measurements provide novel constraints on hadronisation and its Monte Carlo description. In particular, they demonstrate that the fragmentation of jets alone is insufficient to describe the strange and multi-strange particle production in hadronic collisions at LHC energies.
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