We present an analysis of the existing data on charmonium hadro-production based on non-relativistic QCD (NRQCD) calculations at the next-to-leading order (NLO). All the data on J/ψ and ψ(2S) ...production in fixed-target experiments and on pp collisions at low energy are included. We find that the amount of color-octet contribution needed to describe the data is about 1/10 of that found at the Tevatron.
The latest advances in the design and characterization of several pixel sensors developed to satisfy the very demanding requirements of the innermost layer of the SuperB Silicon Vertex Tracker will ...be presented in this paper. The SuperB machine is an electron positron collider operating at the ϒ(4S) peak to be built in the very near future by the Cabibbo Lab consortium. A pixel detector based on extremely thin, radiation hard devices able to cope with rate in the tens of MHz/cm2 range will be the optimal solution for the upgrade of the inner layer of the SuperB tracking system. At present several options with different levels of maturity are being investigated to understand advantages and potential issues of the different technologies: thin hybrid pixels, Deep N-Well CMOS MAPS, INMAPS CMOS MAPS featuring a quadruple well and high resistivity substrates and CMOS MAPS realized with Vertical Integration technology. The newest results from beam test, the outcomes of the radiation damage studies and the laboratory characterization of the latest prototypes will be reported.
The data acquisition system of the SuperB-SVT beam test Sbarra, C.; Fabbri, L.; Gabrielli, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2013, Letnik:
718
Journal Article
Recenzirano
Prototypes of a new hybrid pixel detector and a high resistivity detector with short strips, developed by the VIPIX Collaboration and aimed at equipping the layer-0 of the SuperB vertex detector, ...have been tested in September 2011 with a 120GeV pion beam at the SPS H6 beam line at CERN. They are placed at the center of a reference telescope consisting of six planes of silicon detector with a double-sided strip readout. Both the telescope and the detectors under test (DUT) are equipped with a custom-design, data-push digital readout. The main elements of the trigger and data acquisition system are two VME boards (EDRO) organized in a master-slave configuration and responsible for programming the front-end chips of both the telescope and the DUT. The master board distributes a global synchronization clock and the triggers to all devices, including two 3×3 analog-maps matrices placed behind the DUT and supplied with an independent readout. Both EDROs act as event-fragment builders. These are sent out to a remote PC for event building, buffering and storage.
Measurements of the kinematic distributions of
J
/
ψ
mesons produced in
p
–C,
p
–Ti and
p
–W collisions at
in the Feynman-
x
region −0.34<
x
F
<0.14 and for transverse momentum up to
p
T
=5.4 GeV/c ...are presented. The
x
F
and
p
T
dependencies of the nuclear suppression parameter,
α
, are also given. The results are based on 2.4×10
5
J
/
ψ
mesons reconstructed in both the
e
+
e
−
and
μ
+
μ
−
decay channels. The data have been collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The measurement explores the negative region of
x
F
for the first time. The average value of
α
in the measured
x
F
region is 0.981±0.015. The data suggest that the strong nuclear suppression of
J
/
ψ
production previously observed at high
x
F
turns into an enhancement at negative
x
F
.
The antineutron–proton total cross section has been measured in the low momentum range 50–400 MeV/
c (below 100 MeV/
c for the first time). The measurement was performed at LEAR (CERN) by the OBELIX ...experiment, thanks to its unique antineutron beam facility. A thick target transmission technique has been used. The measured total cross section shows an anomalous behaviour below 100 MeV/
c. A dominance of the isospin
I=0 channel over the
I=1 one at low energy is clearly deduced.
The computing cluster built at Bologna to provide the LHCb Collaboration with a powerful Monte Carlo production tool is presented. It is a performance oriented Beowulf-class cluster, made of rack ...mounted commodity components, designed to minimize operational support requirements and to provide full and continuous availability of the computing resources. In this paper we describe the architecture of the cluster, and discuss the technical solutions adopted for each specialized sub-system.
A study of the angular distributions of leptons from decays of
J
/
ψ
’s produced in p-C and p-W collisions at
has been performed in the
J
/
ψ
Feynman-
x
region −0.34<
x
F
<0.14 and for
J
/
ψ
...transverse momenta up to 5.4 GeV/
c
. The data were collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The results, based on a clean selection of 2.3×10
5
J
/
ψ
’s reconstructed in both the
e
+
e
−
and
μ
+
μ
−
decay channels, indicate that
J
/
ψ
’s are produced polarized. The magnitude of the effect is maximal at low
p
T
. For
p
T
>1 GeV/
c
a significant dependence on the reference frame is found: the polar anisotropy is more pronounced in the Collins-Soper frame and almost vanishes in the helicity frame, where, instead, a significant azimuthal anisotropy arises.
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