We present a measurement of multiple Coulomb scattering of 1 to 6 GeV/c electrons in thin (50-140 um) silicon targets. The data were obtained with the EUDET telescope Aconite at DESY and are compared to parametrisations as used in the Geant4 software package. We find good agreement between data and simulation in the scattering distribution width but large deviations in the shape of the distribution. In order to achieve a better description of the shape, a new scattering model based on a Students t distribution is developed and compared to the data.
We discuss a technique for measuring a charged particles momentum by means of multiple Coulomb scattering (MCS) in the MicroBooNE liquid argon time projection chamber (LArTPC). This method does not require the full particle ionization track to be contained inside of the detector volume as other track momentum reconstruction methods do (range-based momentum reconstruction and calorimetric momentum reconstruction). We motivate use of this technique, describe a tuning of the underlying phenomenological formula, quantify its performance on fully contained beam-neutrino-induced muon tracks both in simulation and in data, and quantify its performance on exiting muon tracks in simulation. Using simulation, we have shown that the standard Highland formula should be re-tuned specifically for scattering in liquid argon, which significantly improves the bias and resolution of the momentum measurement. With the tuned formula, we find agreement between data and simulation for contained tracks, with a small bias in the momentum reconstruction and with resolutions that vary as a function of track length, improving from about 10% for the shortest (one meter long) tracks to 5% for longer (several meter) tracks. For simulated exiting muons with at least one meter of track contained, we find a similarly small bias, and a resolution which is less than 15% for muons with momentum below 2 GeV/c. Above 2 GeV/c, results are given as a first estimate of the MCS momentum measurement capabilities of MicroBooNE for high momentum exiting tracks.
Multiple scattering effects of 12 and 20 GeV electrons on 8 and 20 mm thickness carbon targets have been studied with high-resolution silicon microstrip detectors of the UA9 apparatus at the H8 line at CERN. Comparison of the scattering angle between data and GEANT4 simulation shows excellent agreement in the core of the distributions leaving some residual disagreement in the tails.
Ultra-Fast Silicon Detectors (UFSDs) are n-in-p silicon detectors that implement moderate gain (typically 5 to 25) using a thin highly doped p++ layer between the high resistivity p-bulk and the junction of the sensor. The presence of gain allows excellent time measurement for impinging minimum ionizing charged particles. An important design consideration is the sensor thickness, which has a strong impact on the achievable time resolution. We present the result of measurements for LGADs of thickness between 20 micro-m and 50 micro-m. The data are fit to a formula that captures the impact of both electronic jitter and Landau fluctuations on the time resolution. The data illustrate the importance of having a saturated electron drift velocity and a large signal-to-noise in order to achieve good time resolution. Sensors of 20 micro-m thickness offer the potential of 10 to 15 ps time resolution per measurement, a significant improvement over the value for the 50 micro-m sensors that have been typically used to date.
The tracking detector of ATLAS, one of the experiments at the Large Hadron Collider (LHC), will be upgraded in 2024-2026 to cope with the challenging environment conditions of the High Luminosity LHC (HL-LHC). The LPNHE, in collaboration with FBK and INFN, has produced 130~$mu$m thick $n-on-p$ silicon pixel sensors which can withstand the expected large particle fluences at HL- LHC, while delivering data at high rate with excellent hit efficiency. Such sensors were tested on beam before and after irradiation both at CERN-SPS and at DESY, and their performances are presented in this paper. Beam test data indicate that these detectors are suited for all the layers where planar sensors are foreseen in the future ATLAS tracker: hit-efficiency is greater than 97% for fluences $Phi lesssim 7times10^{15}rm{n_{eq}/cm^2}$ and module power consumption is within the specified limits. Moreover, at a fluence $Phi = 1.3times10^{16}rm{n_{eq}/cm^2}$, hit-efficiency is still as high as 88% and charge collection efficiency is about 30%.
Reflectance of silicon photomultipliers (SiPMs) is an important aspect to understand the large scale SiPM-based detector systems and evaluate the performance of SiPMs. We report the reflactance of two SiPMs, NUV-HD-lowCT and S14160-60-50HS manufactured by Fondazione Bruno Kessler (FBK) and Hamamatsu Photonics K.K. (HPK) respectively, in linear alkylbenzene (LAB) and in air at visible wavelengths. Our results show that the reflectance of the FBK SiPM in air varies in the range of 14% to 23% , depending on wavelengths and angle of incidence, which is 2 time larger than that of the HPK device. This indicates that the two manufacturers are using different designs of anti-reflective coating on SiPMs surfaces. The reflectance is reduced by about 10% when SiPMs are immersed in LAB, compared with that measured in air. The profiles of reflected light beams are also measured by a charge-coupled device (CCD) camera for the two SiPMs.