2,117 research outputs found
Charged particle detection performances of CMOS pixel sensors produced in a 0.18 um process with a high resistivity epitaxial layer
The apparatus of the ALICE experiment at CERN will be upgraded in 2017/18
during the second long shutdown of the LHC (LS2). A major motivation for this
upgrade is to extend the physics reach for charmed and beauty particles down to
low transverse momenta. This requires a substantial improvement of the spatial
resolution and the data rate capability of the ALICE Inner Tracking System
(ITS). To achieve this goal, the new ITS will be equipped with 50 um thin CMOS
Pixel Sensors (CPS) covering either the 3 innermost layers or all the 7 layers
of the detector. The CPS being developed for the ITS upgrade at IPHC
(Strasbourg) is derived from the MIMOSA 28 sensor realised for the STAR-PXL at
RHIC in a 0.35 um CMOS process. In order to satisfy the ITS upgrade
requirements in terms of readout speed and radiation tolerance, a CMOS process
with a reduced feature size and a high resistivity epitaxial layer should be
exploited. In this respect, the charged particle detection performance and
radiation hardness of the TowerJazz 0.18 um CMOS process were studied with the
help of the first prototype chip MIMOSA 32. The beam tests performed with
negative pions of 120 GeV/c at the CERN-SPS allowed to measure a
signal-to-noise ratio (SNR) for the non-irradiated chip in the range between 22
and 32 depending on the pixel design. The chip irradiated with the combined
dose of 1 MRad and 10^13 n_eq/cm^2 was observed to yield a SNR ranging between
11 and 23 for coolant temperatures varying from 15 C to 30 C. These SNR values
were measured to result in particle detection efficiencies above 99.5% and 98%
before and after irradiation respectively. These satisfactory results allow to
validate the TowerJazz 0.18 um CMOS process for the ALICE ITS upgrade.Comment: (v2) Added hyper-links; (v3) A typo correcte
Development of CMOS Pixel Sensors fully adapted to the ILD Vertex Detector Requirements
CMOS Pixel Sensors are making steady progress towards the specifications of
the ILD vertex detector. Recent developments are summarised, which show that
these devices are close to comply with all major requirements, in particular
the read-out speed needed to cope with the beam related background. This
achievement is grounded on the double- sided ladder concept, which allows
combining signals generated by a single particle in two different sensors, one
devoted to spatial resolution and the other to time stamp, both assembled on
the same mechanical support. The status of the development is overviewed as
well as the plans to finalise it using an advanced CMOS process.Comment: 2011 International Workshop on Future Linear Colliders (LCWS11),
Granada, Spain, 26-30 September 201
Odyssey 2 : A mission toward Neptune and Triton to test General Relativity
Odyssey 2 will be proposed in December 2010 for the next call of M3 missions
for Cosmic Vision 2015-2025. This mission, under a Phase 0 study performed by
CNES, will aim at Neptune and Triton. Two sets of objectives will be pursued.
The first one is to perform a set of gravitation experiments at the Solar
System scale. Experimental tests of gravitation have always shown good
agreement with General Relativity. There are however drivers to continue
testing General Relativity, and to do so at the largest possible scales. From a
theoretical point of view, Einstein's theory of gravitation shows
inconsistencies with a quantum description of Nature and unified theories
predict deviations from General Relativity. From an observational point of
view, as long as dark matter and dark energy are not observed through other
means than their gravitational effects, they can be considered as a
manifestation of a modification of General Relativity at cosmic scales. The
scientific objectives are to: (i) test the gravitation law at the Solar System
scale; (ii) measure the Eddington parameter; and (iii) investigate the
navigation anomalies during fly-bys. To fulfil these objectives, the following
components are to be on board the spacecraft: (i) the Gravity Advanced Package
(GAP), which is an electrostatic accelerometer to which a rotating stage is
added; (ii) radio-science; (iii) laser ranging, to improve significantly the
measure of the Eddington parameter. The second set of objectives is to enhance
our knowledge of Neptune and Triton. Several instruments dedicated to
planetology are foreseen: camera, spectrometer, dust and particle detectors,
and magnetometer. Depending on the ones kept, the mission could provide
information on the gravity field, the atmosphere and the magnetosphere of the
two bodies as well as on the surface geology of Triton and on the nature of the
planetary rings around Neptune.Comment: 61st International Astronautical Congress (Prague, Czech Republic -
September 2010), 7 page
Optimisation of CMOS pixel sensors for high performance vertexing and tracking
CMOS Pixel Sensors tend to become relevant for a growing spectrum of charged
particle detection instruments. This comes mainly from their high granularity
and low material budget. However, several potential applications require a
higher read-out speed and radiation tolerance than those achieved with
available devices based on a 0.35 micrometers feature size technology. This
paper shows preliminary test results of new prototype sensors manufactured in a
0.18 micrometers process based on a high resistivity epitaxial layer of
sizeable thickness. Grounded on these observed performances, we discuss a
development strategy over the coming years to reach a full scale sensor
matching the specifications of the upgraded version of the Inner Tracking
System (ITS) of the ALICE experiment at CERN, for which a sensitive area of up
to about 10 square meters may be equipped with pixel sensors.Comment: Presented at the Vienna Conference on Instrumentation 2013 4 pages, 5
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A Time Projection Chamber with GEM-Based Readout
For the International Large Detector concept at the planned International
Linear Collider, the use of time projection chambers (TPC) with micro-pattern
gas detector readout as the main tracking detector is investigated. In this
paper, results from a prototype TPC, placed in a 1 T solenoidal field and read
out with three independent GEM-based readout modules, are reported. The TPC was
exposed to a 6 GeV electron beam at the DESY II synchrotron. The efficiency for
reconstructing hits, the measurement of the drift velocity, the space point
resolution and the control of field inhomogeneities are presented.Comment: 22 pages, 19 figure
Nominal Henkin Semantics: simply-typed lambda-calculus models in nominal sets
We investigate a class of nominal algebraic Henkin-style models for the
simply typed lambda-calculus in which variables map to names in the denotation
and lambda-abstraction maps to a (non-functional) name-abstraction operation.
The resulting denotations are smaller and better-behaved, in ways we make
precise, than functional valuation-based models.
Using these new models, we then develop a generalisation of \lambda-term
syntax enriching them with existential meta-variables, thus yielding a theory
of incomplete functions. This incompleteness is orthogonal to the usual notion
of incompleteness given by function abstraction and application, and
corresponds to holes and incomplete objects.Comment: In Proceedings LFMTP 2011, arXiv:1110.668
Recommendations for radiation therapy in oligometastatic prostate cancer:An ESTRO-ACROP Delphi consensus
Background and purpose: Oligometastatic prostate cancer is a new and emerging treatment field with only few prospective randomized studies published so far. Despite the lack of strong level I evidence, metastasis-directed therapies (MDT) are widely used in clinical practice, mainly based on retrospective and small phase 2 studies and with a large difference across centers. Pending results of ongoing prospec-tive randomized trials, there is a clear need for more consistent treatment indications and radiotherapy practices.Material and methods: A European Society for Radiotherapy and Oncology (ESTRO) Guidelines Committee consisting of radiation oncologists' experts in prostate cancer was asked to answer a dedicated question-naire, including 41 questions on the main controversial issues with regard to oligometastatic prostate cancer.Results: The panel achieved consensus on patient selection and routine use of prostate-specific mem-brane antigen positron emission tomography (PSMA PET) imaging as preferred staging and restaging imaging. MDT strategies are recommended in the de novo oligometastatic, oligorecurrent and oligopro-gressive disease setting for nodal, bone and visceral metastases. Radiation therapy doses, volumes and techniques were discussed and commented.Conclusion: These recommendations have the purpose of providing standardization and consensus to optimize the radiotherapy treatment of oligometastatic prostate cancer until mature results of random-ized trials are available.AT would like to acknowledge the support of Cancer Research UK (C33589/A28284 and C7224/A28724) . This project represents independent research supported by the National Institute for Health research (NIHR) Biomedical Research Centre at The Royal Marsden NHS Foundation Trust and the Institute of Cancer Research, London. The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care
Preliminary results of lifetime measurements in neutron-rich 53Ti
To study the nuclear structure of neutron-rich titanium isotopes, a lifetime measurement was performed at the Grand Accélérateur National d'Ions Lourds (GANIL) facility in Caen, France. The nucleiwere produced in a multinucleon-transfer reaction by using a 6.76 MeV/u 238U beam. The Advanced Gamma Tracking Array (AGATA) was employed for the γ-ray detection and target-like recoils were identified event-by-event by the large-acceptance variable mode spectrometer (VAMOS++). Preliminary level lifetimes of the (5/2−) to 13/2− states of the yrast band in the neutron-rich nucleus 53Ti were measured for the first time employing the recoil distance Doppler-shift (RDDS) method and the compact plunger for deep inelastic reactions. The differential decay curve method (DDCM) was used to obtain the lifetimes from the RDDS data
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