Abstract
The planned HL-LHC (High Luminosity LHC) in 2025 is being designed to maximise the physics potential through a sizable increase in the luminosity up to 6·1034 cm−2s−1. A consequence of this increased luminosity is the expected radiation damage at 3000 fb−1 after ten years of operation, requiring the tracking detectors to withstand fluences to over 1·1016 1 MeV neq/cm2. In order to cope with the consequent increased readout rates, a complete re-design of the current ATLAS Inner Detector (ID) is being developed as the Inner Tracker (ITk).Two proposed detectors for the ATLAS strip tracker region of the ITk were characterized at the Diamond Light Source with a 3 μm FWHM 15 keV micro focused X-ray beam. The devices under test were a 320 μm thick silicon stereo (Barrel) ATLAS12 strip mini sensor wire bonded to a 130 nm CMOS binary readout chip (ABC130) and a 320 μm thick full size radial (end-cap) strip sensor - utilizing bi-metal readout layers - wire bonded to 250 nm CMOS binary readout chips (ABCN-25).A resolution better than the inter strip pitch of the 74.5 μm strips was achieved for both detectors. The effect of the p-stop diffusion layers between strips was investigated in detail for the wire bond pad regions.Inter strip charge collection measurements indicate that the effective width of the strip on the silicon sensors is determined by p-stop regions between the strips rather than the strip pitch.
Highlights
DevicesThe devices investigated in the testbeam were constructed as as possible to the required future strip tracker modules, given current availability of components [7]
- Alternative glues for the production of ATLAS silicon strip modules for the PhaseII upgrade of the ATLAS Inner Detector L
They do, allow for a comparison of the width of a sensor area connected to one readout channel with the nominal strip widths of each sensor
Summary
The devices investigated in the testbeam were constructed as as possible to the required future strip tracker modules, given current availability of components [7]. Aluminium wedge wire bonding was used both to connect the sensor strips and ASIC readout channels and to connect the ASICs and hybrid electrically. Both tested devices are described in detail 2.1 and 2.2. The performance of all readout channels, such as input noise and gain, was determined using known injected charges, generated on calibration capacitors present on the ASIC Using these measurements, all channels were trimmed to have comparable thresholds: in absence of any signal in the sensor, all channels were adjusted to use the same threshold starting point (corresponding to 0 fC input charge), see table 1
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