A ug 2 00 5 The ATLAS Pixel Detector
The ATLAS Pixel Detector is the innermost layer of the ATLAS tracking system and will contribute significantly to the ATLAS track and vertex reconstruction. The detector consists of identical modules, arranged in three barrels concentric wi th the beam line and centered on the interaction point and three dis ks on either side for the forward region. The position of the Pixel Detector near the interaction point requires excellent radiation hardness, mechanical and the rmal robustness and good long-term stability, all combined witha low material budget. The detector layout, results from production modules and the status of assembly are presented.
MCC: The Module Controller Chip for the ATLAS pixel detector
In this article we describe the architecture of the Module Controller Chip for the ATLAS Pixel Detector. The project started in 1997 with the definition of the system specifications. A first fully-working rad-soft prototype was designed in 1998, while a radiation hard version was submitted in 2000. The 1998 version was used to build pixel detector modules. Results from those modules and from the simulated performance in ATLAS are reported. In the article we also describe the hardware/software tools developed to test the MCC performance at the LHC event rate.
Climatology of the cusp-related thermospheric mass density anomaly, as derived from CHAMP observations
We report on the thermospheric mass density anomaly in the vicinity of the ionospheric cusp. A systematic survey of the anomalies is presented, based on a statistical analysis of 4 years of data (2002–2005) obtained by the accelerometer onboard CHAMP. The anomalies are detected during all years and seasons in both hemispheres but with stronger signatures in the Northern Hemisphere. For the same geophysical conditions, solar flux and geomagnetic activity the anomalies in the north are larger by a factor of about 1.35. Over the course of the survey period the amplitude decreases by more than a factor of 5 while the level of solar flux reduces by a factor of 2. The anomaly strength also depends on the solar wind input. The merging electric field, E merg , is generally enhanced for about an hour before the anomaly detection. There is a quadratic response of the anomaly amplitude to E merg . For geophysical conditions of P10.7 E merg E merg , where the weight of E merg , in mV/m, is by about 50 times higher than that of the solar flux level. The solar zenith angle and the influence of particle precipitation are found to play a minor role as a controlling parameter of seasonal variation. The well-known annual variation of the thermospheric density with a minimum around June also influences the formation of the cusp anomalies. This leads to a clear hemispheric asymmetry with very weak anomalies in the south during June solstice, which is supposed to be a combined effect of the minimum in annual variation and the seasonal decrease of solar insolation in this region.