511 research outputs found
Performance of novel silicon n-in-p planar Pixel Sensors
The performance of novel n-in-p planar pixel detectors, designed for future
upgrades of the ATLAS Pixel system is presented. The n-in-p silicon sensors
technology is a promising candidate for the pixel upgrade thanks to its
radiation hardness and cost effectiveness, that allow for enlarging the area
instrumented with pixel detectors. The n-in-p modules presented here are
composed of pixel sensors produced by CiS connected by bump-bonding to the
ATLAS readout chip FE-I3. The characterization of these devices has been
performed before and after irradiation up to a fluence of 5 x 10**15 1 MeV neq
cm-2 . Charge collection measurements carried out with radioactive sources have
proven the functioning of this technology up to these particle fluences. First
results from beam test data with a 120 GeV/c pion beam at the CERN-SPS are also
discussed, demonstrating a high tracking efficiency of (98.6 \pm 0.3)% and a
high collected charge of about 10 ke for a device irradiated at the maximum
fluence and biased at 1 kV.Comment: Preprint submitted to Nuclear Instruments and Methods A. 7 pages, 13
figure
Heavily Irradiated N-in-p Thin Planar Pixel Sensors with and without Active Edges
We present the results of the characterization of silicon pixel modules
employing n-in-p planar sensors with an active thickness of 150
m, produced at MPP/HLL, and 100-200 m thin active
edge sensor devices, produced at VTT in Finland. These thin sensors are
designed as candidates for the ATLAS pixel detector upgrade to be operated at
the HL-LHC, as they ensure radiation hardness at high fluences. They are
interconnected to the ATLAS FE-I3 and FE-I4 read-out chips. Moreover, the
n-in-p technology only requires a single side processing and thereby it is a
cost-effective alternative to the n-in-n pixel technology presently employed in
the LHC experiments. High precision beam test measurements of the hit
efficiency have been performed on these devices both at the CERN SpS and at
DESY, Hamburg. We studied the behavior of these sensors at different bias
voltages and different beam incident angles up to the maximum one expected for
the new Insertable B-Layer of ATLAS and for HL-LHC detectors. Results obtained
with 150 m thin sensors, assembled with the new ATLAS FE-I4 chip
and irradiated up to a fluence of
410, show that they are
excellent candidates for larger radii of the silicon pixel tracker in the
upgrade of the ATLAS detector at HL-LHC. In addition, the active edge
technology of the VTT devices maximizes the active area of the sensor and
reduces the material budget to suit the requirements for the innermost layers.
The edge pixel performance of VTT modules has been investigated at beam test
experiments and the analysis after irradiation up to a fluence of
510 has been performed
using radioactive sources in the laboratory.Comment: Proceedings for iWoRiD 2013 conference, submitted to JINS
Thin n-in-p pixel sensors and the SLID-ICV vertical integration technology for the ATLAS upgrade at the HL-LHC
The R&D activity presented is focused on the development of new modules for
the upgrade of the ATLAS pixel system at the High Luminosity LHC (HL-LHC). The
performance after irradiation of n-in-p pixel sensors of different active
thicknesses is studied, together with an investigation of a novel
interconnection technique offered by the Fraunhofer Institute EMFT in Munich,
the Solid-Liquid-InterDiffusion (SLID), which is an alternative to the standard
solder bump-bonding. The pixel modules are based on thin n-in-p sensors, with
an active thickness of 75 um or 150 um, produced at the MPI Semiconductor
Laboratory (MPI HLL) and on 100 um thick sensors with active edges, fabricated
at VTT, Finland. Hit efficiencies are derived from beam test data for thin
devices irradiated up to a fluence of 4e15 neq/cm^2. For the active edge
devices, the charge collection properties of the edge pixels before irradiation
is discussed in detail, with respect to the inner ones, using measurements with
radioactive sources. Beyond the active edge sensors, an additional ingredient
needed to design four side buttable modules is the possibility of moving the
wire bonding area from the chip surface facing the sensor to the backside,
avoiding the implementation of the cantilever extruding beyond the sensor area.
The feasibility of this process is under investigation with the FE-I3 SLID
modules, where Inter Chip Vias are etched, employing an EMFT technology, with a
cross section of 3 um x 10 um, at the positions of the original wire bonding
pads.Comment: Proceedings for Pixel 2012 Conference, submitted to NIM A, 6 page
Production and Characterisation of SLID Interconnected n-in-p Pixel Modules with 75 Micrometer Thin Silicon Sensors
The performance of pixel modules built from 75 micrometer thin silicon
sensors and ATLAS read-out chips employing the Solid Liquid InterDiffusion
(SLID) interconnection technology is presented. This technology, developed by
the Fraunhofer EMFT, is a possible alternative to the standard bump-bonding. It
allows for stacking of different interconnected chip and sensor layers without
destroying the already formed bonds. In combination with Inter-Chip-Vias (ICVs)
this paves the way for vertical integration. Both technologies are combined in
a pixel module concept which is the basis for the modules discussed in this
paper.
Mechanical and electrical parameters of pixel modules employing both SLID
interconnections and sensors of 75 micrometer thickness are covered. The
mechanical features discussed include the interconnection efficiency, alignment
precision and mechanical strength. The electrical properties comprise the
leakage currents, tuning characteristics, charge collection, cluster sizes and
hit efficiencies. Targeting at a usage at the high luminosity upgrade of the
LHC accelerator called HL-LHC, the results were obtained before and after
irradiation up to fluences of
(1 MeV neutrons).Comment: 16 pages, 22 figure
Novel Silicon n-in-p Pixel Sensors for the future ATLAS Upgrades
In view of the LHC upgrade phases towards HL-LHC the ATLAS experiment plans
to upgrade the Inner Detector with an all silicon system. The n-in-p silicon
technology is a promising candidate for the pixel upgrade thanks to its
radiation hardness and cost effectiveness, that allow for enlarging the area
instrumented with pixel detectors. We present the characterization and
performance of novel n-in-p planar pixel sensors produced by CiS (Germany)
connected by bump bonding to the ATLAS readout chip FE-I3. These results are
obtained before and after irradiation up to a fluence of 10^16 1-MeV n_eq/cm^2,
and prove the operability of this kind of sensors in the harsh radiation
environment foreseen for the pixel system at HL-LHC. We also present an
overview of the new pixel production, which is on-going at CiS for sensors
compatible with the new ATLAS readout chip FE-I4.Comment: Preprint submitted to NIM-A Proceedings (Elba 2012
Characterization of Thin Pixel Sensor Modules Interconnected with SLID Technology Irradiated to a Fluence of 2\,n/cm
A new module concept for future ATLAS pixel detector upgrades is presented,
where thin n-in-p silicon sensors are connected to the front-end chip
exploiting the novel Solid Liquid Interdiffusion technique (SLID) and the
signals are read out via Inter Chip Vias (ICV) etched through the front-end.
This should serve as a proof of principle for future four-side buttable pixel
assemblies for the ATLAS upgrades, without the cantilever presently needed in
the chip for the wire bonding.
The SLID interconnection, developed by the Fraunhofer EMFT, is a possible
alternative to the standard bump-bonding. It is characterized by a very thin
eutectic Cu-Sn alloy and allows for stacking of different layers of chips on
top of the first one, without destroying the pre-existing bonds. This paves the
way for vertical integration technologies.
Results of the characterization of the first pixel modules interconnected
through SLID as well as of one sample irradiated to \,\neqcm{}
are discussed.
Additionally, the etching of ICV into the front-end wafers was started. ICVs
will be used to route the signals vertically through the front-end chip, to
newly created pads on the backside. In the EMFT approach the chip wafer is
thinned to (50--60)\,m.Comment: Proceedings to PSD
Performance of n-in-p pixel detectors irradiated at fluences up to 5x10**15 neq/cm**2 for the future ATLAS upgrades
We present the results of the characterization of novel n-in-p planar pixel
detectors, designed for the future upgrades of the ATLAS pixel system. N-in-p
silicon devices are a promising candidate to replace the n-in-n sensors thanks
to their radiation hardness and cost effectiveness, that allow for enlarging
the area instrumented with pixel detectors. The n-in-p modules presented here
are composed of pixel sensors produced by CiS connected by bump-bonding to the
ATLAS readout chip FE-I3. The characterization of these devices has been
performed with the ATLAS pixel read-out systems, TurboDAQ and USBPIX, before
and after irradiation with 25 MeV protons and neutrons up to a fluence of
5x10**15 neq /cm2. The charge collection measurements carried out with
radioactive sources have proven the feasibility of employing this kind of
detectors up to these particle fluences. The collected charge has been measured
to be for any fluence in excess of twice the value of the FE-I3 threshold,
tuned to 3200 e. The first results from beam test data with 120 GeV pions at
the CERN-SPS are also presented, demonstrating a high tracking efficiency
before irradiation and a high collected charge for a device irradiated at
10**15 neq /cm2. This work has been performed within the framework of the RD50
Collaboration.Comment: Proceedings of the Conference "Technology and Instrumentation in
Particle Physics 2011
Striatal glucose metabolism and dopamine D2 receptor binding in asymptomatic gene carriers and patients with Huntington's disease
We used PET scans with the tracers [18F]fluorodeoxyglucose (FDG) and [11C]raclopride (RACLO) to study glucose metabolism and dopamine D2 receptor binding in the caudate nucleus and putamen of 18 carriers of the Huntington's disease gene mutation (10 asymptomatic subjects and eight untreated symptomatic Huntington's disease patients in an early disease stage). We also performed MR1 scans and measured the bicaudate ratio (BCR) in the same subjects. Data were compared with those from nine mutation-negative members of Huntington's disease families and separate groups of age matched controls. The PET scans were repeated 1.5-3 years later in six of the asymptomatic gene carriers. Symptomatic Huntington's disease patients showed a marked reduction of FDG and RACLO uptake in the caudate nucleus and putamen and a significant increase of BCR. Asymptomatic mutation carriers revealed significant hypometabolism in the caudate nucleus and putamen. The RACLO binding was significantly decreased in the putamen. Decrements of caudate nucleus tracer uptake, particularly RACLO, correlated significantly with BCR increases in both symptomatic and asymptomatic gene carriers. In asymptomatic carriers, metabolic and receptor binding decreases were also significantly associated with the CAG repeat number but not with the individual's age. Discriminant function analysis correctly classified clinical and genetic status in 24 of 27 subjects on the basis of their striatal PET values (83% sensitivity and 100% specificity). Three asymptomatic mutation carriers were classified/grouped together with mutation-negative subjects, indicating that these individuals had normal striatal RACLO and FDG uptake. Follow-up PET data from gene-positive subjects showed a significant reduction in the mean striatal RACLO binding of 6.3% per year. Striatal glucose metabolism revealed an overall non significant 2.3% decrease per year These data indicate that asymptomatic Huntington's disease mutation carriers may show normal neuronal function for a long period of life. These findings also suggest that it may be possible to predict when an asymptomatic gene carrier will develop clinical symptoms from serial PET measurements of striatal functio
Prototype ATLAS IBL Modules using the FE-I4A Front-End Readout Chip
The ATLAS Collaboration will upgrade its semiconductor pixel tracking
detector with a new Insertable B-layer (IBL) between the existing pixel
detector and the vacuum pipe of the Large Hadron Collider. The extreme
operating conditions at this location have necessitated the development of new
radiation hard pixel sensor technologies and a new front-end readout chip,
called the FE-I4. Planar pixel sensors and 3D pixel sensors have been
investigated to equip this new pixel layer, and prototype modules using the
FE-I4A have been fabricated and characterized using 120 GeV pions at the CERN
SPS and 4 GeV positrons at DESY, before and after module irradiation. Beam test
results are presented, including charge collection efficiency, tracking
efficiency and charge sharing.Comment: 45 pages, 30 figures, submitted to JINS
Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC
The uncertainty on the calorimeter energy response to jets of particles is
derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the
calorimeter response to single isolated charged hadrons is measured and
compared to the Monte Carlo simulation using proton-proton collisions at
centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009
and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter
response to specific types of particles (positively and negatively charged
pions, protons, and anti-protons) is measured and compared to the Monte Carlo
predictions. Finally, the jet energy scale uncertainty is determined by
propagating the response uncertainty for single charged and neutral particles
to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3%
for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table,
submitted to European Physical Journal
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