Abstract
The High Luminosity LHC (HL-LHC) upgrade requires the
planned Inner Tracker (ITk) of the ATLAS detector to tolerate
extremely high radiation doses. Specifically, the innermost parts of
the ...pixel system will have to withstand radiation fluences above
1 × 10
16
n
eq
cm
-2
. Novel 3D silicon pixel
sensors offer a superior radiation tolerance compared to
conventional planar pixel sensors, and are thus excellent candidates
for the innermost parts of the ITk. This paper presents studies of
3D pixel sensors with pixel size 50 × 50 μm
2
mounted
on the RD53A prototype readout chip. Following a description of the
design and fabrication steps, Test Beam results are presented for
unirradiated as well as heavily irradiated sensors. For particles
passing at perpendicular incidence, it is shown that average
efficiencies above 96% are reached for sensors exposed to fluences
of 1 × 10
16
n
eq
cm
-2
when biased to 80 V.
The ATLAS Forward Proton (AFP) detector is designed to identify events in which one or two protons emerge intact from the LHC collisions. AFP will consist of a tracking detector, to measure the ...momentum of the protons, and a time of flight system to reduce the background from multiple proton-proton interactions. Following an extensive qualification period, 3D silicon pixel sensors were selected for the AFP tracker. The sensors were produced at CNM (Barcelona) during 2014. The tracker module assembly and quality control was performed at IFAE during 2015. The assembly of the first AFP arm and the following installation in the LHC tunnel took place in February 2016. This paper reviews the fabrication process of the AFP tracker focusing on the pixel modules.
For the purpose of withstanding very high radiation doses, silicon pixel sensors with a `3D' electrode geometry are being developed. Detectors of this kind are highly interesting for harch radiation ...environments such as expected in the High Luminosity LHC, but also for space physics and medical applications. In this paper, prototype sensors developed at SINTEF are presented and results from tests in a pion beam at CERN are given. These tests show that these 3D sensors perform as expected with full efficiency at bias voltages between 5 and 15V.
COMPET is a preclinical PET scanner aiming towards a high sensitivity, a high resolution and MRI compatibility by implementing a novel detector geometry. In this approach, long scintillating LYSO ...crystals are used to absorb the γ-rays. To determine the point of interaction (POI) between γ-ray and crystal, the light exiting the crystals on one of the long sides is collected with wavelength shifters (WLS) perpendicularly arranged to the crystals. This concept has two main advantages: (1) The parallax error is reduced to a minimum and is equal for the whole field of view (FOV). (2) The POI and its energy deposit is known in all three dimension with a high resolution, allowing for the reconstruction of Compton scattered γ-rays. Point (1) leads to a uniform point source resolution (PSR) distribution over the whole FOV, and also allows to place the detector close to the object being imaged. Both points (1) and (2) lead to an increased sensitivity and allow for both high resolution and sensitivity at the same time, while keeping a low number of readout channels.
In total, COMPET incorporates 1080 readout channels (600 crystals, 480 WLS). It has an axial FOV of 80mm and adjustable bore opening between 30mm and 80mm. It consists of four modules with five layers each. Simulations show a PSR of below 1mm in the transaxial plane and a sensitivity of up to 16% in the center of the FOV. The readout is based on time over threshold signals, sampled with an FPGA, which allows for the measurement of high event rates at the order of mega-counts per seconds. Its compact design and compatibility to high magnetic fields will allow to use it as an insert for an already existing MRI scanner.
A first semi-layer with 12 WLS and 10 LYSO crystal was built and connected to the COMPET readout system. Coincidence data between this module and a tagger crystal using a small Ge-68 and a 60MBq F-18 source was taken.
3D silicon pixel sensors: Recent test beam results Hansson, P.; Balbuena, J.; Barrera, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2011, Letnik:
628, Številka:
1
Journal Article
Recenzirano
The 3D silicon sensors aimed for the ATLAS pixel detector upgrade have been tested with a high energy pion beam at the CERN SPS in 2009. Two types of sensor layouts were tested: full-3D assemblies ...fabricated in Stanford, where the electrodes penetrate the entire silicon wafer thickness, and modified-3D assemblies fabricated at FBK-irst with partially overlapping electrodes. In both cases three read-out electrodes are ganged together to form pixels of dimension
50
×
400
μ
m
2
. Data on the pulse height distribution, tracking efficiency and resolution were collected for various particle incident angles, with and without a 1.6
T magnetic field. Data from a planar sensor of the type presently used in the ATLAS detector were used at the same time to give comparison.
COMPET is an innovative implementation of a small animal PET scanner using a novel block detector geometry, allowing for a high resolution and high sensitivity. One detector block is built up from ...layers of long LYSO crystals. Perpendicular and interleaved between the crystals, Wave Length Shifting (WLS) fibers are used. The scintillation light created by a gamma ray interacting with a crystal is measured with Geiger mode Avalanche Photo Diodes (GAPDs) at one end of the crystals. A small part of the scintillation light escapes the crystals and enters the WLS, where it has a certain probability to be absorbed and re-emitted at a longer wavelength. This light is measured at one end of the WLS by a GAPD. With this setup, the point of interaction (POI) of the gamma ray is deduced, allowing for the 3D reconstruction of the interaction point between the gamma ray and the detector. Thus, not only photoelectric interactions are used to reconstruct the line of responses (LOR) for each event, but also Compton scattered gamma-rays are included. Using 4 such modules, the total detector comprises a total amount of 1080 readout channels, where 600 are used for the crystals and 480 for the WLS. The central point source resolution was deduced from Monte Carlo simulation to be below 1 mm FWHM in transaxial direction. The sensitivity to detect coincident gamma rays emitted at the centre of the field of view is up to 16%. With its compact geometry, high point source resolution, high sensitivity and its low amount of readout channels, the COMPET detector geometry provides a promising detector layout for future preclinical PET scanners.
The ATLAS Semiconductor Tracker (SCT) consists of four barrel cylinders and 18 end-cap disks. This paper describes the SCT modules of the barrel region, of which more than 2000 are about to be ...constructed. The module design is fixed. Its design concept is given together with the electrical, thermal and mechanical specifications. The pre-series production of the barrel modules is underway using mass-production procedures and jigs. The pre-series modules have given satisfactory performances on noise, noise occupancy, electrical as well as mechanical and thermal properties. In addition, irradiated modules were demonstrated to work successfully. Also first results from a 10-module system test are given.
The ATLAS SemiConductor Tracker (SCT) is one of the largest existing semiconductor detectors. It is situated between the Pixel detector and the Transition Radiation Tracker at one of the four ...interaction points of the Large Hadron Collider (LHC). During 2006-2007 the detector was lowered into the ATLAS cavern and installed in its final position. For the assembly, integration and commissioning phase, a complete Detector Control System (DCS) was developed to ensure the safe operation of the tracker. This included control of the individual powering of the silicon modules, a bi-phase cooling system and various types of sensors monitoring the SCT environment and the surrounding test enclosure. The DCS software architecture, performance and operational experience will be presented in the view of a validation of the DCS for the final SCT installation and operation phase.
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