The European X-ray Free Electron Laser (XFEL), currently being constructed in Hamburg and planning to be operational in 2017 for users, will deliver 27,000 fully coherent, high brilliance X-ray pulses per second with duration less than 100 fs. The unique features of the X-ray beam pose major challenges for detectors used at the European XFEL for imaging experiments, in particular a radiation tolerance of silicon sensors for doses up to 1 GGy for 3 years of operation at an operating voltage above 500 V.One of the detectors under development at the European XFEL is the Adaptive Gain Integrating Pixel Detector (AGIPD), which is a hybrid detector system with ASICs bump-bonded to p + n silicon pixel sensors. We have designed the silicon sensors for the AGIPD, which have been fabricated by SINTEF and delivered in the beginning of February of 2013. To demonstrate the performance of the AGIPD sensor with regard to radiation hardness, mini-sensors with the same pixel and guard-ring designs as the AGIPD together with test structures have been irradiated at the beamline P11 of PETRA III with 8 keV and 12 keV monoenergetic X-rays to dose values up to 10 MGy. The radiation hardness of the AGIPD sensor has been proven and all electrical properties are within specification before and after irradiation. In addition, the oxide-charge density and surface-current density from test structures have been characterized as function of the X-ray dose and compared to previous measurements for test structures produced by four vendors.
The ATLAS experiment is constructing new all-silicon inner
tracking system for HL-LHC. The strip detectors cover the radial
extent of 40 to 100 cm. A new approach is adopted to use p-type
silicon material, making the readout in n+-strips, so-called
n+-in-p sensors. This allows for enhanced radiation tolerance
against an order of magnitude higher particle fluence compared to
the LHC. To cope with varying hit rates and occupancies as a
function of radial distance, there are two barrel sensor types, the
short strips (SS) for the inner 2 and the long strips (LS) for the
outer 2 barrel cylinders, respectively. The barrel sensors exhibit a
square, 9.8 × 9.8 cm2, geometry, the largest possible
sensor area from a 6-inch wafer. The strips are laid out in
parallel with a strip pitch of 75.5 μm and 4 or 2 rows of
strip segments. The strips are AC-coupled and biased via
polysilicon resistors. The endcap sensors employ a
“stereo-annulus” geometry exhibiting a skewed-trapezoid shapes
with circular edges. They are designed in 6 unique shapes, R0 to R5,
corresponding to progressively increasing radial extents and which
allows them to fit within the petal geometry and the 6-inch wafer
maximally. The strips are in fan-out geometry with an in-built
rotation angle, with a mean pitch of approximately 75 μm and
4 or 2 rows of strip segments. The eight sensor types are labeled
as ATLAS18xx where xx stands for SS, LS, and R0 to R5. According to
the mechanical and electrical specifications, CAD files for wafer
processing were laid out, following the successful designs of
prototype barrel and endcap sensors, together with a number of
optimizations. A pre-production was carried out prior to the full
production of the wafers. The quality of the sensors is reviewed
and judged excellent through the test results carried out by vendor.
These sensors are used for establishing acceptance procedures and to
evaluate their performance in the ATLAS collaboration, and
subsequently for pre-production of strip modules and stave and petal
structures.
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