Abstract
The high luminosity upgrade of the LHC is targeted to deliver 3000fb−1 at a luminosity of 5×1034cm−2s−1. Higher granularity, 140 collisions per bunch crossing and existing bandwidth limitations require a reduction of the amount of data at module level. New modules have binary readout, on-chip pT discrimination and capabilities to provide track finding data at 40MHz to the L1-trigger. The CMS collaboration has undertaken R&D effort to develop new planar sensors for the pixel-strip (PS) module, which has to withstand 1×1015cm−2 1MeV neutron equivalent fluence in the innermost layer of the tracker. The module is composed of a strip sensor and a macro pixel sensor with 100μm×1.5mm pixel size. Sensors were characterized in the laboratory and the effects of different process parameters and sensor concepts were studied. This contribution presents a new sensor prototype with n-pixels in p-bulk material in planar technology for the PS module. A new inverted module concept is presented, which has advantages with respect to the baseline concept. Electrical characterization of sensors and SEM-images are presented.
Highlights
The current CMS tracker [1] needs a major upgrade, which is developed for an integrated design luminosity of 3000 fb−1 at an instantaneous luminosity of 5 × 1034 cm−2s−1 during the HLLHC phase [2]
140 collisions per bunch crossing and existing bandwidth limitations require a reduction of the amount of data at module level
Sensors were characterized in the laboratory and the effects of different process parameters and sensor concepts were studied
Summary
The current CMS tracker [1] needs a major upgrade, which is developed for an integrated design luminosity of 3000 fb−1 at an instantaneous luminosity of 5 × 1034 cm−2s−1 during the HLLHC phase [2]. During HL-LHC the CMS tracker must work at an estimated pile-up of 140 at 25 ns bunch spacing. This has to be addressed at module level. Binary readout of the modules and on chip pT-discrimination is necessary, in order to include the tracker in the trigger decision and to reduce the data rate. Sensor has 6 rows of 38 columns of 100 μm × 1.6 mm pixels and a width to pitch ratio of 0.25. The foreseen readout chip is the Macro Pixel ASIC (MPA) with integrated stub finding logic for pT-discrimination [4]. The sensors implant width is 125 μm and the pitch is 200 μm at the readout chip boundaries. Surface resistivity and p-stop concentration, pstop width and geometry adjust the current. 200 μm thickness of the active volume was selected and n-in-p technology was chosen as a result of previous studies [5]
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