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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Barranco Navarro, L., Cabrera Urban, S., et al. (2019). Modelling radiation damage to pixel sensors in the ATLAS detector. J. Instrum., 14, P06012–52pp.
Abstract: Silicon pixel detectors are at the core of the current and planned upgrade of the ATLAS experiment at the LHC. Given their close proximity to the interaction point, these detectors will be exposed to an unprecedented amount of radiation over their lifetime. The current pixel detector will receive damage from non-ionizing radiation in excess of 10(15) 1 MeV n(eq)/cm(2), while the pixel detector designed for the high-luminosity LHC must cope with an order of magnitude larger fluence. This paper presents a digitization model incorporating effects of radiation damage to the pixel sensors. The model is described in detail and predictions for the charge collection efficiency and Lorentz angle are compared with collision data collected between 2015 and 2017 (<= 10(15) 1 MeV n(eq)/cm(2)).
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Garcia, A. R., Martinez, T., Cano-Ott, D., Castilla, J., Guerrero, C., Marin, J., et al. (2012). MONSTER: a time of flight spectrometer for beta-delayed neutron emission measurements. J. Instrum., 7, C05012–12pp.
Abstract: The knowledge of the beta-decay properties of nuclei contributes decisively to our understanding of nuclear phenomena: the beta-delayed neutron emission of neutron rich nuclei plays an important role in the nucleosynthesis r-process and constitutes a probe for nuclear structure of very neutron rich nuclei providing information about the high energy part of the full beta strength (S-beta) function. In addition, beta-delayed neutrons are essential for the control and safety of nuclear reactors. In order to determine the neutron energy spectra and emission probabilities from neutron precursors a MOdular Neutron time-of-flight SpectromeTER (MONSTER) has been proposed for the DESPEC experiment at the future FAIR facility. The design of MONSTER and status of its construction are reported in this work.
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Gomez-Cadenas, J. J., Benlloch-Rodriguez, J. M., & Ferrario, P. (2017). Monte Carlo study of the coincidence resolving time of a liquid xenon PET scanner, using Cherenkov radiation. J. Instrum., 12, P08023–13pp.
Abstract: In this paper we use detailed Monte Carlo simulations to demonstrate that liquid xenon (LXe) can be used to build a Cherenkov-based TOF-PET, with an intrinsic coincidence resolving time (CRT) in the vicinity of 10 ps. This extraordinary performance is due to three facts: a) the abundant emission of Cherenkov photons by liquid xenon; b) the fact that LXe is transparent to Cherenkov light; and c) the fact that the fastest photons in LXe have wavelengths higher than 300 nm, therefore making it possible to separate the detection of scintillation and Cherenkov light. The CRT in a Cherenkov LXe TOF-PET detector is, therefore, dominated by the resolution (time jitter) introduced by the photosensors and the electronics. However, we show that for sufficiently fast photosensors (e.g, an overall 40 ps jitter, which can be achieved by current micro-channel plate photomultipliers) the overall CRT varies between 30 and 55 ps, depending on the detection efficiency. This is still one order of magnitude better than commercial CRT devices and improves by a factor 3 the best CRT obtained with small laboratory prototypes.
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Double Chooz collaboration(Abrahao, T. et al), & Novella, P. (2018). Novel event classification based on spectral analysis of scintillation waveforms in Double Chooz. J. Instrum., 13, P01031–26pp.
Abstract: Liquid scintillators are a common choice for neutrino physics experiments, but their capabilities to perform background rejection by scintillation pulse shape discrimination is generally limited in large detectors. This paper describes a novel approach for a pulse shape based event classification developed in the context of the Double Chooz reactor antineutrino experiment. Unlike previous implementations, this method uses the Fourier power spectra of the scintillation pulse shapes to obtain event-wise information. A classification variable built from spectral information was able to achieve an unprecedented performance, despite the lack of optimization at the detector design level. Several examples of event classification are provided, ranging from differentiation between the detector volumes and an efficient rejection of instrumental light noise, to some sensitivity to the particle type, such as stopping muons, ortho-positronium formation, alpha particles as well as electrons and positrons. In combination with other techniques the method is expected to allow for a versatile and more efficient background rejection in the future, especially if detector optimization is taken into account at the design level.
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ATLAS Collaboration(Aad, G. et al), Bernabeu Verdu, J., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fassi, F., et al. (2014). Operation and performance of the ATLAS semiconductor tracker. J. Instrum., 9, P08009–73pp.
Abstract: The semiconductor tracker is a silicon microstrip detector forming part of the inner tracking system of the ATLAS experiment at the LHC. The operation and performance of the semiconductor tracker during the first years of LHC running are described. More than 99% of the detector modules were operational during this period, with an average intrinsic hit efficiency of (99.74 +/- 0.04)%. The evolution of the noise occupancy is discussed, and measurements of the Lorentz angle, delta-ray production and energy loss presented. The alignment of the detector is found to be stable at the few-micron level over long periods of time. Radiation damage measurements, which include the evolution of detector leakage currents, are found to be consistent with predictions and are used in the verification of radiation background simulations.
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ATLAS Collaboration(Aad, G. et al), Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Cardillo, F., et al. (2022). Operation and performance of the ATLAS semiconductor tracker in LHC Run 2. J. Instrum., 17(1), P01013–56pp.
Abstract: The semiconductor tracker (SCT) is one of the tracking systems for charged particles in the ATLAS detector. It consists of 4088 silicon strip sensor modules. During Run 2 (2015-2018) the Large Hadron Collider delivered an integrated luminosity of 156 fb(-1) to the ATLAS experiment at a centre-of-mass proton-proton collision energy of 13 TeV. The instantaneous luminosity and pile-up conditions were far in excess of those assumed in the original design of the SCT detector. Due to improvements to the data acquisition system, the SCT operated stably throughout Run 2. It was available for 99.9% of the integrated luminosity and achieved a data-quality efficiency of 99.85%. Detailed studies have been made of the leakage current in SCT modules and the evolution of the full depletion voltage, which are used to study the impact of radiation damage to the modules. '
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Barrio, J., Etxebeste, A., Lacasta, C., Muñoz, E., Oliver, J. F., Solaz, C., et al. (2015). Performance of VATA64HDR16 ASIC for medical physics applications based on continuous crystals and SiPMs. J. Instrum., 10, P12001–12pp.
Abstract: Detectors based on Silicon Photomultipliers (SiPMs) coupled to continuous crystals are being tested in medical physics applications due to their potential high resolution and sensitivity. To cope with the high granularity required for a very good spatial resolution, SiPM matrices with a large amount of elements are needed. To be able to read the information coming from each individual channel, dedicated ASICs are employed. The VATA64HDR16 ASIC is a 64-channel, charge-sensitive amplifier that converts the collected charge into a proportional current or voltage signal. A complete assessment of the suitability of that ASIC for medical physics applications based on continuous crystals and SiPMs has been carried out. The input charge range is linear from 20 pC up to 55 pC. The energy resolution obtained at 511 keV is 10% FWHM with a LaBr3 crystal and 16% FWHM with a LYSO crystal. A coincidence timing resolution of 24 ns FWHM is obtained with two LYSO crystals.
Keywords: Solid state detectors; Photon detectors for UV, visible and IR photons (solid-state) (PIN diodes, APDs, Si-PMTs, G-APDs, CCDs, EBCCDs, EMCCDs etc); Front-end electronics for detector readout; Gamma detectors (scintillators, CZT, HPG, HgI etc)
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ATLAS Collaboration(Abat, E. et al), Bernabeu Verdu, J., Castillo Gimenez, V., Costa, M. J., Escobar, C., Ferrer, A., et al. (2011). Photon reconstruction in the ATLAS Inner Detector and Liquid Argon Barrel Calorimeter at the 2004 Combined Test Beam. J. Instrum., 6, P04001–40pp.
Abstract: The reconstruction of photons in the ATLAS detector is studied with data taken during the 2004 Combined Test Beam, where a full slice of the ATLAS detector was exposed to beams of particles of known energy at the CERN SPS. The results presented show significant differences in the longitudinal development of the electromagnetic shower between converted and unconverted photons as well as in the total measured energy. The potential to use the reconstructed converted photons as a means to precisely map the material of the tracker in front of the electromagnetic calorimeter is also considered. All results obtained are compared with a detailed Monte-Carlo simulation of the test-beam setup which is based on the same simulation and reconstruction tools as those used for the ATLAS detector itself.
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Boronat, M., Marinas, C., Frey, A., Garcia, I., Schwenker, B., Vos, M., et al. (2015). Physical Limitations to the Spatial Resolution of Solid-State Detectors. IEEE Trans. Nucl. Sci., 62(1), 381–386.
Abstract: In this paper we explore the effect of delta-ray emission and fluctuations in the signal deposition on the detection of charged particles in silicon-based detectors. We show that these two effects ultimately limit the resolution that can be achieved by interpolation of the signal in finely segmented position-sensitive solid-state devices.
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Kuehn, S. et al, Bernabeu, J., Lacasta, C., Marco-Hernandez, R., Santoyo, D., Solaz, C., et al. (2017). Prototyping of hybrids and modules for the forward silicon strip tracking detector for the ATLAS Phase-II upgrade. J. Instrum., 12, P05015–26pp.
Abstract: For the High-Luminosity upgrade of the Large Hadron Collider an increased instantaneous luminosity of up to 7.5 . 10(34) cm(-2) s(-1), leading to a total integrated luminosity of up to 3000 fb(-1), is foreseen. The current silicon and transition radiation tracking detectors of the ATLAS experiment will be unable to cope with the increased track densities and radiation levels, and will need to be replaced. The new tracking detector will consist entirely of silicon pixel and strip detectors. In this paper, results on the development and tests of prototype components for the new silicon strip detector in the forward regions (end-caps) of the ATLAS detector are presented. Flex-printed readout boards with fast readout chips, referred to as hybrids, and silicon detector modules are investigated. The modules consist of a hybrid glued onto a silicon strip sensor. The channels on both are connected via wire-bonds for readout and powering. Measurements of important performance parameters and a comparison of two possible readout schemes are presented. In addition, the assembly procedure is described and recommendations for further prototyping are derived.
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