Topic
Scintillation
About: Scintillation is a research topic. Over the lifetime, 14022 publications have been published within this topic receiving 187694 citations.
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TL;DR: In this paper, a photon trap is used for scintillation light detection in large Time Projection Chambers, where the ratio between the area of the active devices and the optical window can be adjusted.
Abstract: We present a totally innovative device for the detection of liquid argon scintillation light, that has been named ARAPUCA (Argon R&D Advanced Program at UniCAmp). It is composed of a passive light collector and of active devices. The latters are standard SiPMs that operate at liquid argon temperature, while the passive collector is based on a new technology, never explored in this field before. It is a photon trap, that allows to collect light with extremely high efficiency. The total detection efficiency of the device can be tuned by modifying the ratio between the area of the active devices (SiPM) and the area of the optical window. For example, it will allow to reach a detection efficiency at the level of 1% on a surface of 50 × 50 cm2 with an active coverage of 2 × 2 cm2 (two/three large area SiPM). It is also a cheap device, since the major part of its cost is represented by the active devices. For these reason this appears to be the ideal device for scintillation light detection in large Time Projection Chambers. With appropriate modifications it can be used also in next generation Dark Matter detectors.
67 citations
TL;DR: In this article, a systematic overestimate of heat fluxes is found from sodar measurements made during the morning, when the height of the convectively mixed layer is increasing rapidly.
Abstract: Measurements of acoustic backscatter in the lower planetary boundary layer and optical line-of-sight scintillation in the surface layer are each used to compute sensible heat fluxes in the unstable surface layer. Comparisons with simultaneous low-level point measurements by eddy correlation show good agreement, indicating that remote-sensing methods can be successful over less homogeneous terrain where conventional surface layer measurement techniques are less accurate. Corrections to take into account the effects of humidity fluctuations are found necessary in order to achieve accuracies within 10%. Free convection is assumed to permit interpretation of the sodar data, while either forced or free convection is assumed for the scintillation data. A systematic overestimate of heat fluxes is found from sodar measurements made during the morning, when the height of the convectively mixed layer is increasing rapidly.
67 citations
TL;DR: It appears that the worst case scintillation encountered at midlatitudes, including the United States, does not significantly impact L1 carrier‐tracking performance and Semicodeless tracking of the L2 carrier is shown to be very fragile.
Abstract: A scintillation signal model and a Global Positioning System (GPS)-Wide Area Augmentation System (WAAS) receiver model are developed. The scintillation signal model is based on a Nakagami-m distribution for intensity and a Gaussian distribution with zero mean for phase. The GPS-WAAS receiver model includes Link 1 (L1) GPS and WAAS carrier-and C/A-code-tracking loops, as well as semicodeless Link 2 (L2) carrier and Y-code tracking capabilities. The results show that noncoherent delay locked loops (DLLs) typically used for code tracking are very robust to both amplitude and phase scintillation. Carrier-phase-tracking loops are much more susceptible to scintillation, and the signal-to-noise threshold for reliable carrier tracking is very dependent on the scintillation strength. Fortunately, it appears that the worst case scintillation encountered at midlatitudes, including the United States, does not significantly impact L1 carrier-tracking performance. Semicodeless tracking of the L2 carrier is shown to be very fragile. Even weak scintillation can cause loss of L2 carrier lock for low-elevation satellites.
67 citations
TL;DR: In this article, the difference in the amplitude variation rate for rain attenuation and scintillation fading is used to extract the effects of the two phenomena individually from raw data with the aid of a filtering technique.
Abstract: Signal-level variations on Ku-band low-elevation Earth-space paths, where large signal fades due to rain and tropospheric scintillations sometimes occur simultaneously, are examined. The difference in the amplitude variation rate for rain attenuation and scintillation fading is used to extract the effects of the two phenomena individually from raw data with the aid of a filtering technique. Characteristics of signal fading during rain are discussed on the basis of the analysis. It is shown that the decrease of signal level due to scintillation is much smaller than that due to rain attenuation, particularly for time percentages below 0.1%. However, for time percentages above about 1%, the effect of scintillation becomes dominant and no longer negligible, particularly for low-margin systems operating at low elevation angles. >
67 citations
24 Sep 2004
TL;DR: In this paper, a GPS ionospheric scintillation and TEC monitor (GISTM) is deployed in a near-equatorial location in Africa (Douala, Camaroon -- 4o01’N, 9o43’E).
Abstract: A GPS Ionospheric Scintillation and TEC Monitor (GISTM) has been deployed in a near-equatorial location in Africa (Douala, Camaroon -- 4o01’N, 9o43’E). The new feature of this receiver is that it can also measure the amplitude and phase scintillation indices on the SBAS signal received from a geostationary satellite. This observation, with its fixed link geometry, is particularly interesting for the analysis of temporal variation in the scintillation behavior of the equatorial ionosphere. At the same time it allows a direct assessment of the threat posed by scintillation to the SBAS signal. This paper presents the experimental setup, the principle behind the measurements and the first results.
67 citations