270,132 research outputs found
From vertex detectors to inner trackers with CMOS pixel sensors
The use of CMOS Pixel Sensors (CPS) for high resolution and low material
vertex detectors has been validated with the 2014 and 2015 physics runs of the
STAR-PXL detector at RHIC/BNL. This opens the door to the use of CPS for inner
tracking devices, with 10-100 times larger sensitive area, which require
therefore a sensor design privileging power saving, response uniformity and
robustness. The 350 nm CMOS technology used for the STAR-PXL sensors was
considered as too poorly suited to upcoming applications like the upgraded
ALICE Inner Tracking System (ITS), which requires sensors with one order of
magnitude improvement on readout speed and improved radiation tolerance. This
triggered the exploration of a deeper sub-micron CMOS technology, Tower-Jazz
180 nm, for the design of a CPS well adapted for the new ALICE-ITS running
conditions. This paper reports the R&D results for the conception of a CPS well
adapted for the ALICE-ITS.Comment: 4 pages, 4 figures, VCI 2016 conference proceeding
Evaluating Visual Conversational Agents via Cooperative Human-AI Games
As AI continues to advance, human-AI teams are inevitable. However, progress
in AI is routinely measured in isolation, without a human in the loop. It is
crucial to benchmark progress in AI, not just in isolation, but also in terms
of how it translates to helping humans perform certain tasks, i.e., the
performance of human-AI teams.
In this work, we design a cooperative game - GuessWhich - to measure human-AI
team performance in the specific context of the AI being a visual
conversational agent. GuessWhich involves live interaction between the human
and the AI. The AI, which we call ALICE, is provided an image which is unseen
by the human. Following a brief description of the image, the human questions
ALICE about this secret image to identify it from a fixed pool of images.
We measure performance of the human-ALICE team by the number of guesses it
takes the human to correctly identify the secret image after a fixed number of
dialog rounds with ALICE. We compare performance of the human-ALICE teams for
two versions of ALICE. Our human studies suggest a counterintuitive trend -
that while AI literature shows that one version outperforms the other when
paired with an AI questioner bot, we find that this improvement in AI-AI
performance does not translate to improved human-AI performance. This suggests
a mismatch between benchmarking of AI in isolation and in the context of
human-AI teams.Comment: HCOMP 201
Exhibiting the ALICE experiment
Among the many outreach and communication tools available in our digital era,
traditional tools such as exhibitions still hold an important place. The ALICE
collaboration is setting up a new exhibition at the experiment's site, as part
of the ALICE Visitor Centre. Its goal is to communicate to visitors the physics
and the tools and methods used by ALICE. It combines modern technology such as
video mapping with real detector items, aiming to fascinate the visitors and
give them an immersive experience of a high energy physics experiment. The
development process, the messages to be delivered and the choices for the
contents and the way of exhibiting them are discussed; and the final design and
present status of the project are presented.Comment: 6 pages, 9 figures, Fifth Annual Large Hadron Collider Physics
Conferenc
The Transition Radiation Detector for ALICE at LHC
The Transition Radiation Detector (TRD) for the ALICE experiment at the Large
Hadron Collider (LHC) identifies electrons in p+p and in the challenging high
multiplicity environment of heavy-ion collisions and provides fast online
tracking for the ALICE Level1 trigger. The TRD is designed to have excellent
position resolution and pion rejection capability. Presently, six of the 18 TRD
supermodules are installed in the ALICE central barrel. In 2008, four
supermodules were installed and commissioning of the detector using cosmic ray
tracks was successfully performed. We briefly describe the design of the
detector and report on the performance and current understanding of the
detector based on these data.Comment: 4 pages, 6 figures - To appear in the conference proceedings for
Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse
Alice: The Rosetta Ultraviolet Imaging Spectrograph
We describe the design, performance and scientific objectives of the
NASA-funded ALICE instrument aboard the ESA Rosetta asteroid flyby/comet
rendezvous mission. ALICE is a lightweight, low-power, and low-cost imaging
spectrograph optimized for cometary far-ultraviolet (FUV) spectroscopy. It will
be the first UV spectrograph to study a comet at close range. It is designed to
obtain spatially-resolved spectra of Rosetta mission targets in the 700-2050 A
spectral band with a spectral resolution between 8 A and 12 A for extended
sources that fill its ~0.05 deg x 6.0 deg field-of-view. ALICE employs an
off-axis telescope feeding a 0.15-m normal incidence Rowland circle
spectrograph with a concave holographic reflection grating. The imaging
microchannel plate detector utilizes dual solar-blind opaque photocathodes (KBr
and CsI) and employs a 2 D delay-line readout array. The instrument is
controlled by an internal microprocessor. During the prime Rosetta mission,
ALICE will characterize comet 67P/Churyumov-Gerasimenko's coma, its nucleus,
and the nucleus/coma coupling; during cruise to the comet, ALICE will make
observations of the mission's two asteroid flyby targets and of Mars, its
moons, and of Earth's moon. ALICE has already successfully completed the
in-flight commissioning phase and is operating normally in flight. It has been
characterized in flight with stellar flux calibrations, observations of the
Moon during the first Earth fly-by, and observations of comet Linear T7 in 2004
and comet 9P/Tempel 1 during the 2005 Deep Impact comet-collision observing
campaignComment: 11 pages, 7 figure
Material Budget Calculation of the new Inner Tracking System, ALICE
The ALICE Collaboration aims at studying the physics of strongly interacting
matter by building up a dedicated heavy-ion detector. The Inner Tracking System
(ITS) is located in the heart of the ALICE Detector surrounding the interaction
point. Now, ALICE has a plan to upgrade the inner tracking system for rare
probes at low transverse momentum. The new ITS composes of seven layers of
silicon pixel sensor on the supporting structure. One goal of the new design is
to reduce the material budget () per layer to 0.3 for inner layers
and 0.8 for middle and outer layers. In this work, we perform the
calculations based on detailed geometry descriptions of different supporting
structures for inner and outer barrel using ALIROOT. Our results show that it
is possible to reduce the material budget of the inner and outer barrel to the
value that we have expected. The manufacturing of such prototypes are also
possible.Comment: 13 pages, 9 figures, regular pape
Study of D-mesons using hadronic decay channels with the ALICE detector
At LHC energy, heavy quarks will be abundantly produced and the design of the
ALICE Experiment will allow us to study their production using several
channels. We investigate the feasibility of the study of D mesons reconstructed
in their exclusive hadronic decay channel. After reviewing the ALICE potential
for such studies, we will present some results for the two more promising decay
channels i.e D0->KPi and D+ -> K-Pi+Pi+ obtained with 7 TeV pp data and 5.5 A
TeV Pb-Pb Monte Carlo data .Comment: 4 Pages, 5 Figures. Conference Proceeding to be published in Nuclear
Physics
The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events
The design, construction, and commissioning of the ALICE Time-Projection
Chamber (TPC) is described. It is the main device for pattern recognition,
tracking, and identification of charged particles in the ALICE experiment at
the CERN LHC. The TPC is cylindrical in shape with a volume close to 90 m^3 and
is operated in a 0.5 T solenoidal magnetic field parallel to its axis.
In this paper we describe in detail the design considerations for this
detector for operation in the extreme multiplicity environment of central
Pb--Pb collisions at LHC energy. The implementation of the resulting
requirements into hardware (field cage, read-out chambers, electronics),
infrastructure (gas and cooling system, laser-calibration system), and software
led to many technical innovations which are described along with a presentation
of all the major components of the detector, as currently realized. We also
report on the performance achieved after completion of the first round of
stand-alone calibration runs and demonstrate results close to those specified
in the TPC Technical Design Report.Comment: 55 pages, 82 figure
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