Speaker
Description
The Timepix detector network inside the ATLAS cavern has proven to be effective in measuring luminosity and the radiation field composition during LHC Run-2 operation [1]. First tests of Timepix3 in this radiation environment provided promising results so that for Run-3, the network has been upgraded to a two-layer detector stack relying fully on the Timepix3 technology. Each two-layer Timepix3 detectors is equipped with neutron converters (${}^{6}$LiF and polyethylene) for spectrum resolved neutron detection. These detectors were installed at different locations within the ATLAS experiment where they provide a continuous measurement of the radiation levels and the radiation field composition. All devices are synchronized with the LHC orbit clock allowing for bunch-resolved luminosity determination.
Within the present work we will provide an overview of the capabilities of the installed detector network with a focus on evaluating its performance for relative luminosity measurement. We present an assessment of observed noise patterns which were identified by statistical methods (single-pixel noise) and by comparison of the signal of different detectors with each other (full-matrix noise).
Luminosity measurement is performed with the different units inside the network. Each unit provides a set of different algorithms. In cluster counting the overall cluster rate is used. Hereby, by using the continuous measurement of the noise corrected radiation levels during and after collision periods, the relative contribution of induced radioactivity to the overall count rate is estimated to be 3-10$\%$ depending on the location within ATLAS. We further evaluate neutron and MIP counting algorithm, which provide activation-independent measurement by utilizing only traces of shapes which are rarely produced by gamma-rays.
Within this contribution we compare the different algorithms and different units with each other to assess systematic uncertainties, the sensitivity to luminosity according to the location and properties inside the cavern and present a short-term and long-term stability. For the innermost detectors we evaluate the capability to perform a bunch-by-bunch analysis.
Figure: Long-term analysis of the main detectors using the cluster counting algorithm comparing to their average for the LHC fills between April 30th to October 16th of 2024
References:
[1] B. Bergmann et al., “Characterization of the Radiation Field in the ATLAS Experiment with Timepix Detectors”, in IEEE Transactions on Nuclear Science 66, no. 7, pp. 1861-1869 (2019) \url{https://ieeexplore.ieee.org/abstract/document/8720202}
[2] P. Burian et al. “Timepix3 detector network at ATLAS experiment” JINST 13 C11024 (2018) \url{https://iopscience.iop.org/article/10.1088/1748-0221/13/11/C11024/meta}
[3] B. Bergmann et al., “Relative luminosity measurement with Timepix3 in ATLAS” JINST 15 C01039 (2020). \url{https://iopscience.iop.org/article/10.1088/1748-0221/15/01/C01039/meta}
| Workshop topics | Applications |
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