ATLAS Muon Drift Tube Electronics

Abstract

This paper describes the electronics used for the ATLAS monitored drift tube (MDT) chambers. These chambers are the main component of the precision tracking system in the ATLAS muon spectrometer. The MDT detector system consists of 1,150 chambers containing a total of 354,000 drift tubes. It is capable of measuring the sagitta of muon tracks to an accuracy of 60 µm, which corresponds to a momentum accuracy of about 10% at p T = 1 TeV. The design and performance of the MDT readout electronics as well as the electronics for controlling, monitoring and powering the detector will be discussed. These electronics have been extensively tested under simulated running conditions and have undergone radiation testing certifying them for more than 10 years of LHC operation. They are now installed on the ATLAS detector and are operating during cosmic ray commissioning runs.

Streamlined calibration of the ATLAS Muon Spectrometer precision chambers

“…Part of deposited charge is also read out, but not considered further here. Technically, the readout time is the discriminator threshold crossing time of the anode signal collected by chamber mounted frontend readout electronics [5] [6]. The drift time is this threshold crossing relative to that of a zero impact parameter track, one passing at the wire.…”

Commissioning of the ATLAS Muon Spectrometer with cosmic rays

“…The points correspond to the mean value of the distribution of residuals and the error bars to its RMS value. Residual systematics at the level of 50 μm are present using this correction spect to the front-end electronics clock [15]. This implies a time jitter corresponding to a 25 ns uniform distribution.…”

“…2. Here the average number of hits per tube for each MDT is represented in a η-φ plot where the higher cosmic illumination on the top and bottom sectors (3)(4)(5)(6)(7)(11)(12)(13)(14)(15) compared to the vertical sectors (16-2 and 8-10) is clearly seen as well as the larger illumination on the A side of the detector where the larger shaft is present. The five chambers not included in the data acquisition are marked as dark gray boxes.…”

Performance of the new Amplifier-Shaper-Discriminator chip for the ATLAS MDT chambers at the HL-LHC

“…Higher hit rates, mainly due to increased cavern background, drive data transmission to the rear end electronics to the limit of available bandwidth. In addition, the new operating parameters of the L1 trigger -latency up to 60 µs and trigger rates up to 400 kHz -call for a replacement of the entire readout chain of the MDT chambers.In this process of renewing the MDT readout, particular attention must be given to the first stage of the readout chain, the Amplifier with Shaping network and Discriminator (ASD) [2]. This stage determines critical quantities, like signal risetime, signal-to-noise performance and threshold uniformity among the 8 channels of the chip, which are decisive for system parameters like spatial resolution of the track coordinates (represented by the drift time in the MDT tubes) and tracking efficiency.…”

“…In this process of renewing the MDT readout, particular attention must be given to the first stage of the readout chain, the Amplifier with Shaping network and Discriminator (ASD) [2]. This stage determines critical quantities, like signal risetime, signal-to-noise performance and threshold uniformity among the 8 channels of the chip, which are decisive for system parameters like spatial resolution of the track coordinates (represented by the drift time in the MDT tubes) and tracking efficiency.…”