High resolution pixel detectors for e+e- linear colliders

The physics goals at the future e+e- linear collider require high performance vertexing and impact parameter resolution. Two possible technologies for the vertex detector of an experimental apparatus are outlined in the paper: an evolution of the Hybrid Pixel Sensors already used in high energy physics experiments and a new detector concept based on the monolithic CMOS sensors.Comment: 8 pages, to appear on the Proceedings of the International Workshop on Linear Colliders LCWS99, Sitges (Spain), April 28 - May 5, 199

AlphaRad, a new integrated CMOS System-on-Chip for high efficiency alpha particles counting

An integrated System-on-Chip (SoC) has been designed in 0.6 \mu m CMOS mixed analog/digital technology, and tested for high rate alpha particle Counting. The sensor is the most innovative part of the chip, with a total active area of 2 x 2.5 mm x 5 mm. The two-stage charge-to-voltage amplification scheme includes a numerical block for offset compensation. Designed with a gain of 700, the chip has been tested in alpha sources: a very high signal over noise ratio was obtained, leading to a detection efficiency of 5 MeV alpha particles close to 100%. The chip is working at room temperature and has been tested tip to 300 kHz reset frequency. Future applications of this SoC will focus on detection of fast and thermal neutrons free of gamma contamination

Novel recoil nuclei detectors to qualify the AMANDE facility as a Standard for mono-energetic neutron fields

The AMANDE facility at IRSN-Cadarache produces mono-energetic neutron fields from 2 keV to 20 MeV with metrological quality. To be considered as a standard facility, characteristics of neutron field i.e fluence distribution must be well known by a device using absolute measurements. The development of new detector systems allowing a direct measurement of neutron energy and fluence has started in 2006. Using the proton recoil telescope principle with the goal of increase the efficiency, two systems with full localization are studied. A proton recoil telescope using CMOS sensor (CMOS-RPT) is studied for measurements at high energies and the helium 4 gaseous micro-time projection chamber (microTPC He4) will be dedicated to the lowest energies. Simulations of the two systems were performed with the transport Monte Carlo code MCNPX, to choose the components and the geometry, to optimize the efficiency and detection limits of both devices or to estimate performances expected. First preliminary measurements realised in 2008 demonstrated the proof of principle of these novel detectors for neutron metrology.Comment: to appear in Radiation Measurements, Proc. of 24th International Conference on Nuclear Tracks in Solids (Bologna, 1-5 September 2008

Detector and Front-end electronics for ALICE and STAR silicon strip layers

Detector modules consisting of Silicon Strip Detector (SSD) and Front End Electronics (FEE) assembly have been designed in order to provide the two outer layers of the ALICE Inner Tracker System (ITS) [1] as well as the outer layer of the STAR Silicon Vertex Tracker (SVT) [2]. Several prototypes have beenproduced and tested in the SPS and PS beam at CERN to validate the final design. Double-sided, AC-coupled SSD detectors provided by two different manufacturers and also a pair of single-sided SSD have been asssociated to new low-power CMOS ALICE128C ASIC chips in a new detector module assembly. The same detectors have also been associated to current Viking electronics for reference purpose. These prototype detector modules are described and some first results are presented

Retinoic Acid Restores Adult Hippocampal Neurogenesis and Reverses Spatial Memory Deficit in Vitamin A Deprived Rats

A dysfunction of retinoid hippocampal signaling pathway has been involved in the appearance of affective and cognitive disorders. However, the underlying neurobiological mechanisms remain unknown. Hippocampal granule neurons are generated throughout life and are involved in emotion and memory. Here, we investigated the effects of vitamin A deficiency (VAD) on neurogenesis and memory and the ability of retinoic acid (RA) treatment to prevent VAD-induced impairments. Adult retinoid-deficient rats were generated by a vitamin A-free diet from weaning in order to allow a normal development. The effects of VAD and/or RA administration were examined on hippocampal neurogenesis, retinoid target genes such as neurotrophin receptors and spatial reference memory measured in the water maze. Long-term VAD decreased neurogenesis and led to memory deficits. More importantly, these effects were reversed by 4 weeks of RA treatment. These beneficial effects may be in part related to an up-regulation of retinoid-mediated molecular events, such as the expression of the neurotrophin receptor TrkA. We have demonstrated for the first time that the effect of vitamin A deficient diet on the level of hippoccampal neurogenesis is reversible and that RA treatment is important for the maintenance of the hippocampal plasticity and function

Etude et caractérisation d'un dosimètre neutrons rapides à base de PADC - Study and characterization of a fast neutron dosimeter based on PADC

Polyallyl Diglycol Carbonate (PADC) type PN3 is a polymeric solid state nuclear track detector which is widely used for neutron dosimetry. In this paper, we present the response of PN3 dosimeters for use in fast neutron measurements. PN3 detectors associated with a polyethylene (PE) or PN3 radiator or without radiator were exposed to Am-Be neutrons to evaluate their effectiveness as fast neutron dosimeters. The detectors were chemically etched and track counting was performed using an automated system. It was found that the dosimeter responses were linear up to a neutron dose equivalent of at least 200 mSv and that the simple PN3 detector without radiator (but after pre-etch) has the same response as the two-element dosimeters and thus appears as a promising fast neutron dosimeter Le Polyallyl Diglycol Carbonate (PADC) de type PN3 est un détecteur solide de traces nucléaires qui est largement utilisé en dosimétrie neutrons. Dans ce travail, nous avons étudié la réponse des dosimètres PN3 pour la détection des neutrons rapides. Trois dosimètres constitués d'un détecteur PN3 sans radiateur, d'un détecteur PN3 associé à un radiateur en polyéthylène (PE) et d'un détecteur PN3 associé à un autre détecteur PN3 comme radiateur ont été exposé à une source de neutrons Am-Be. Ces détecteurs ont été développés chimiquement et le comptage de traces a été effectué par système semi automatique. Les résultats obtenus montrent que la fonction de réponse des dosimètres est linéaire en fonction d'équivalent de dose jusqu'au 200 mSv et que le dosimètre PN3 sans radiateur présente une réponse comparable aux deux autres dosimètres et prouve qu'il pourrait être utilisé comme au dosimètre personnel des neutrons rapide

Experimental characterization of a fast, pixelated CMOS sensor and design of a Recoil-Proton Telescope for neutron spectrometry

International audienceNeutrons are particles of interest in various domains such as fundamental physics, biology, elemental analysis or radio-protection. The measurement of the neutron energy is necessary in all these domains, but the required characteristics of the spectrometers can vary greatly from an application to another. The IPHC laboratory is currently developing a new CMOS pixel Recoil Protons Telescope (RPT). This compact detector allows a real-time reconstruction of the neutron spectrum up to very high flux. The pixelated ultra-fast CMOS sensors were characterized in two proton beam experiments. This experimental characterization was then used in a realistic Monte Carlo simulation of the full system to compute the expected performances. The simulated results exhibit very good spectrometric performances, with an energy resolution better than 4% over a 4.5,20MeV energy range. These performances, combined with its compactness and ability to reconstruct the spectrum in real time, make it a very interesting device for various applications

Neutron-based calibration of a Recoil Proton Telescope for fast neutrons spectroscopy

International audienceA Recoil Proton Telescope (RPT), allowing real-time fast neutron spectrometry, has been developed at the IPHC laboratory (Strasbourg, France). The set-up includes a neutron converter, a three-planes tracking part made of pixelated CMOS sensors and a final Si(Li) diode to measure recoil proton energy. The diode calibration is a key component for a precise neutron spectrum reconstruction. The relationship between the charge measured in the diode and the corresponding energy is a function of the temperature and radiation damage, so it must be verified periodically. However, the difficulties to access facilities providing protons with calibrated energies limit the possibility to reassess this calibration on a regular basis. In this paper, we present a straightforward method for RPT neutron-based calibration of the Si(Li) diode which is interesting for high precision measurements at reference neutron sources

Development of an integrated CMOS detector for radon activity measurement and neutron dosimetry

The development of pixel CMOS sensors for particle tracking in high energy physics has led to promising applications for dosimetry. We present the last results in electronic monitoring of atmospheric radon with the new system-on-chip AlphaRad, as well as highly efficient detection of fast neutrons with a megapixel Active Pixel Sensor of the MIMOSA generation