Erratum: The solar orbiter radio and plasma waves (RPW) instrument (Astronomy and Astrophysics (2020) 642 (A12) DOI: 10.1051/0004-6361/201936214)

The erratum concerns Fig. 9 entitled "Antenna radio-electrical properties" for which some of the parameters are not correct. The new figure with new parameters is provided in Fig. 1 of this corrigendum. Fig. 1. Corrected Antenna radio-electrical properties. (Figure Presented)

APD photodetectors in the Geiger photon counter mode

International audienc

APD photodetectors in the Geiger photon counter mode.

International audienceThe best detector in Cerenkov experiments still remains the PM tube, thanks to its characteristics of sensitivity and speed. But its disadvantages are its low quantum efficiency and its cost. We are currently working on solid state silicon detectors, used in the Geiger photon counter mode. We have conducted a series of tests using standard APD, but with an electronic circuitry to raise the polarisation towards the Geiger mode. The photodiode is polarized over its own breakdown bias, one single photon passing through it may start an electron avalanche resulting in about 106 electrons collected. After that, the diode should recover as soon as possible to be available for the next photon. This process is under modelization: electrical diagrams (PSPICE), differential equations (VHDL-AMS) and components physics equations (SABER) are needed to reproduce closely the physical processes and to allow optimisation and improvement of the electronics both for triggering and for the readout of the detectors. Our most promising results will be presented

SiPM cryogenic operation down to 77 K

International audienceSilicon PhotoMultiplier (SiPM) is composed of extremely sensitive photosensors based on the Geiger Mode Avalanche PhotoDiode (GM-APD), which operate as a digital pixel sensitive to single photons. SiPMs are being considered for applications in low temperature environments, such as noble-liquid detectors for dark matter searches or neutrino physics and GM-APD is promising technology for space Compton telescopes. While it is well known that the dark count rate, one of the main limitations of SiPM, is reduced at low temperature, a detailed study of the behavior of the device in cryogenic environment is necessary to assess its performances. In this paper, we present measurements of static parameters as breakdown voltage and quenching resistance of a commercial SiPM (Hamamatsu MPPC S10362-11-100C). Evolution of these parameters as well as junction capacitance between room temperature and 77 K is discussed

APD photodetectors in the Geiger photon counter mode.

International audienceGeiger APD technology, which has been used for a few years now, is evolving towards better performances, including integration in multifunctional Microsystems; one such achievement is today the so-called SiPM [ref 1]. The present work has been conducted by a consortium of researchers from CESR and LAAS/CNRS and the manufacturing of components was achieved in the clean room of LAAS/CNRS. We present here an original N/P technology of photodiode, designed so as to offer a very good homogeneity in the electrical operating characteristics. For this, we have chosen a design and technological process which defines the breakdown voltage from the substrate doping. We present the technological process which we developed, in which we took a special care to maintain, by low transit temperature processes, at the highest quality level the initial characteristics of the materials. We will also present the performances of the diodes produced, with sizes ranging from 10 to 100µm, as a function of many parameters (gain, dark current, etc). We also produced SiPM, and also 8X8 arrays of SiPM. Typical characteristics for a single diode are a Vbr between 43V and 44V, and a dark current below 1 pA at ambient temperature. But the most important feature seems to be the high homogeneity of these performances all over the wafer surface. This gives us a great confidence in the next step of our work, which is the manufacturing of very high sensitivity imaging devices

Geiger avalanche photodiodes as tentative light detectors for VHE gamma ray astronomy

International audienceDue to its sensitivity and speed, the detector still widely used in Cerenkov astrophysics experiments remains the PhotoMultiplier Tube (PMT). For instance, recent pathbreaking experiments in Very High Energy astrophysics (VHE), such as MAGIC and HESS, have used mainstream PMT technology (Aharonian et al, Astron Astrophys 492(1):L25-L28, 2008). Moreover the Cerenkov Telescope Array (CTA) which is now in its design phase, is also planed to be based on PMT's. However, there are some disadvantages to the PMT technology: the rather poor quantum efficiency, the use of high voltages, the high cost when used in large number in a matrix arrangement and the large weight. Hence, we have investigated the possibility to design future Cerenkov telescopes based on solid state technology, specifically Geiger avalanche photodiodes. In a preliminary developmen

Critical sites: a semantic approach to protein sequences. Application to the HIV-1 envelope molecule

We have designed two software systems allowing the study of proteins through a comparison to those stored in data banks. The first one, "Automat", locates in a systematic manner all identities shared by a given protein and the proteins in a data bank. The second, "Critic" enables the selection of specific segments in a given molecule by comparing them with those gathered in a data bank. These sites were termed "critical" since they mostly correspond to functional sites (active sites) of the well-known proteins which were studied with the aid of this program (somatostatin, insulin. IL2, etc). Automat allowed us to reveal homologies between HIV-1 and the CD4, which have remained unsolved until now. These similitudes proved to be critical sites (according to Critic). The putative involvement of these sites in the physiopathological processes as induced by HIV-1 are worth considering since the results of our experiments are consistent with this assumption. HIV / automat / critic / protein. © 1992.SCOPUS: ar.jinfo:eu-repo/semantics/publishe