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 50μm thin CMOS Pixel Sensors (CPS) covering either the three 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 0.35μm 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 TowerJazz0.18μm CMOS process were studied with the help of the first prototype chip MIMOSA 32. The beam tests performed with negative pions of 120GeV/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 1MRad and 1013neq/cm2 was observed to yield an 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 TowerJazz0.18μm CMOS process for the ALICE ITS upgrade.
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CMOS pixel sensors are foreseen to equip the vertex detector (called PXL) of the upgraded inner tracking system of the STAR experiment at RHIC. The sensors (called ULTIMATE) are being designed and ...their architecture is being optimized for the PXL specifications, extrapolating from the MIMOSA-26 sensor realized for the EUDET beam telescope.
The paper gives an overview of the ULTIMATE sensor specifications and of the adaptation of its forerunner, MIMOSA-26, to the PXL specifications.
One of the main changes between MIMOSA-26 and ULTIMATE is the use of a high resistivity epitaxial layer. Recent performance assessments obtained with MIMOSA-26 sensors manufactured on such an epitaxial layer are presented, as well as results of beam tests obtained with a prototype probing improved versions of the MIMOSA-26 pixel design. They show drastic improvements of the pixel signal-to-noise ratio and of the sensor radiation tolerance with respect to the performances achieved with a standard, i.e. low resistivity, layer.
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A novel Monolithic Active Pixel Sensor (MAPS) for charged particle tracking made in a standard CMOS technology is proposed. The sensor is a photodiode, which is readily available in a CMOS ...technology. The diode has a special structure, which allows the high detection efficiency required for tracking applications. The partially depleted thin epitaxial silicon layer is used as a sensitive detector volume. Semiconductor device simulation, using either ToSCA based or 3-D ISE-TCAD software packages shows that the charge collection is efficient, reasonably fast (order of 100
ns), and the charge spreading limited to a few pixels only. A first prototype has been designed, fabricated and tested. It is made of four arrays each containing 64×64 pixels, with a readout pitch of 20
μm in both directions. The device is fabricated using standard submicron 0.6
μm CMOS process, which features twin-tub implanted in a p-type epitaxial layer, a characteristic common to many modern CMOS VLSI processes. Extensive tests made with soft X-ray source (
55Fe) and minimum ionising particles (15
GeV/
c pions) fully demonstrate the predicted performances, with the individual pixel noise (ENC) below 20 electrons and the Signal-to-Noise ratio for both 5.9
keV X-rays and Minimum Ionising Particles (MIP) of the order of 30. This novel device opens new perspectives in high-precision vertex detectors in Particle Physics experiments, as well as in other application, like low-energy beta particle imaging, visible light single photon imaging (using the Hybrid Photon Detector approach) and high-precision slow neutron imaging.
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4.
A single-photon sensitive ebCMOS camera: The LUSIPHER prototype Barbier, R.; Cajgfinger, T.; Calabria, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2011, Volume:
648, Issue:
1
Journal Article
Peer reviewed
Processing high-definition images with single-photon sensitivity acquired above 500 frames per second (fps) will certainly find ground-breaking applications in scientific and industrial domains such ...as nano-photonics. However, current technologies for low light imaging suffer limitations above the standard 30fps to keep providing both excellent spatial resolution and signal-over-noise. This paper presents the state of the art on a promising way to answer this challenge, the electron bombarded CMOS (ebCMOS) detector. A large-scale ultra fast single-photon tracker camera prototype produced with an industrial partner is described. The full characterization of the back-thinned CMOS sensor is presented and a method for Point Spread Function measurements is elaborated. Then the study of the ebCMOS performance is presented for two different multi-alkali cathodes, S20 and S25. Point Spread Function measurements carried out on an optical test bench are analysed to extract the PSF of the tube by deconvolution. The resolution of the tube is studied as a function of temperature, high voltage and incident wavelength. Results are discussed for both multi-alkali cathodes as well as a Maxwellian modelization of the radial initial energy of the photo-electrons.
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ULTIMATE is a reticle size CMOS Pixel Sensor (CPS) designed to meet the requirements of the STAR pixel detector (PXL). It includes a pixel array of 928 rows and 960 columns with a 20.7 mu m pixel ...pitch, providing a sensitive area of similar to 3.8 cm super(2). Based on the sensor designed for the EUDET beam telescope, the device is a binary output sensor with integrated zero suppression circuitry featuring a 320Mbps data throughput capability. It was fabricated in a 0.35 mu m OPTO process early in 2011. The design and preliminary test results, including charged particle detection performances measured at the CERN-SPS, are presented.
Due to their low noise, CMOS Monolithic Active Pixel Sensors are suited to sense X-rays with a few keV quantum energy, which is of interest for high resolution X-ray imaging. Moreover, the good ...energy resolution of the silicon sensors might be used to measure this quantum energy. Combining both features with the good spatial resolution of CMOS sensors opens the potential to build "color sensitive" X-ray cameras. Taking such colored images is hampered by the need to operate the CMOS sensors in a single photon counting mode, which restricts the photon flux capability of the sensors. More importantly, the charge sharing between the pixels smears the potentially good energy resolution of the sensors. Based on our experience with CMOS sensors for charged particle tracking, we studied techniques to overcome the latter by means of an offline processing of the data obtained from a CMOS sensor prototype. We found that the energy resolution of the pixels can be recovered at the expense of reduced quantum efficiency. We will introduce the results of our study and discuss the feasibility of taking colored X-ray pictures with CMOS sensors.
The PLUME (Pixelated Ladder with Ultra-Low Material Embedding) Collaboration is developing ultra-light ladders for the vertex detector for a future linear collider. The double-sided ladder will ...integrate the sensors, readout infrastructure and mechanical supports with the aim of total material budget of 0.3% of radiation length. The requirement of as light as possible construction is driven by physics, in particular by measurements requiring determination of the quark charge sign. The first prototype ladders were prepared and tested in the beam. The alignment issues for the ladders will be tested within the AIDA (Advanced European Infrastructures for Detectors at Accelerators) EU FP7 project.
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9.
Diamond pixel modules Asner, D.; Barbero, M.; Bellini, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2011, Volume:
636, Issue:
1
Journal Article
Peer reviewed
With the commissioning of the LHC in 2010 and upgrades expected in 2015, ATLAS and CMS are planning to upgrade their innermost tracking layers with radiation hard technologies. Chemical Vapor ...Deposition diamond has been used extensively in beam conditions monitors as the innermost detectors in the highest radiation areas of BaBar, Belle, CDF and all LHC experiments. This material is now being considered as a sensor material for use very close to the interaction region where the most extreme radiation conditions exist. Recently the RD42 collaboration constructed, irradiated and tested polycrystalline and single-crystal chemical vapor deposition diamond sensors to the highest fluences expected at the super-LHC. We present beam test results of chemical vapor deposition diamond up to fluences of 1.8×10
16
protons/cm
2 illustrating that both polycrystalline and single-crystal chemical vapor deposition diamonds follow a single damage curve. We also present beam test results of irradiated complete diamond pixel modules.
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10.
Improved radiation tolerance of MAPS using a depleted epitaxial layer Dorokhov, A.; Bertolone, G.; Baudot, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2010, Volume:
624, Issue:
2
Journal Article
Peer reviewed
Tracking performance of Monolithic Active Pixel Sensors (MAPS) developed at IPHC (Turchetta, et al., 2001)
1 have been extensively studied (Winter, et al., 2001; Gornushkin, et al., 2002)
2,3. ...Numerous sensor prototypes, called MIMOSA,
1
1
Standing for Minimum Ionising particle MOS Active pixel sensors.
were fabricated and tested since 1999 in order to optimise the charge collection efficiency and power dissipation, to minimise the noise and to increase the readout speed.
The radiation tolerance was also investigated. The highest fluence tolerable for a
10
μ
m
pitch device was found to be
∼
10
13
n
eq
/
cm
2
, while it was only
2
×
10
12
n
eq
/
cm
2
for a
20
μ
m
pitch device. The purpose of this paper is to show that the tolerance to non-ionising radiation may be extended up to
O(10
14) n
eq/cm
2. This goal relies on a fabrication process featuring a
15
μ
m
thin, high resistivity (
∼
1
k
Ω
cm
) epitaxial layer. A sensor prototype (MIMOSA-25) was fabricated in this process to explore its detection performance. The depletion depth of the epitaxial layer at standard CMOS voltages (
<
5
V
) is similar to the layer thickness. Measurements with m.i.p.s
2
2
Standing for minimum ionising particle.
show that the charge collected in the seed pixel is at least twice larger for the depleted epitaxial layer than for the undepleted one, translating into a signal-to-noise ratio (SNR) of
∼
50
. Tests after irradiation have shown that this excellent performance is maintained up to the highest fluence considered (
3
×
10
13
n
eq
/
cm
2
)
, making evidence of a significant extension of the radiation tolerance limits of MAPS.
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