Session H13: Detectors and Upgrades I

Live

The imaging Time-of-Propagation (iTOP) detector is a novel Cherenkov-based detector developed for particle identification in the central region of the Belle II experiment, which is an upgrade of the previous Belle experiment at KEK. Here we present a general overview of charged particle identification studies in Belle II, with a focus on the performance of the iTOP detector. The results presented are from the most recent data recorded and show reasonable agreement with expecations based on simulation studies.   

Live

The material budget is critical for simulating how particles transverse the detector. Accurately describing where both passive and active material is located is particularly crucial for the tracker where multiple scattering slightly alters the particle's trajectory in the detector. The tracker is also the closest to the interaction point so in order to cope with increasing fluences at the Large Hadron Collider the Compact Muon Solenoid (CMS) pixel detector was upgraded necessitating an upgraded material budget to match the new detector. We will present the material budget for the Phase I pixel upgrade of the CMS detector along with cross checks using data to validate the detector description.   

Live

As part of High Luminosity LHC (HL-LHC) project, the high-granularity calorimeter (HGCAL) will be a major upgrade of CMS experiment to replace the current endcap calorimeter. Due to the higher instantaneous luminosity of the HL-LHC and the rapidity range the HGCAL will cover, radiation tolerance is a primary design consideration. The majority of the HGCAL will be based on 120-, 200-, and 300 \textmu m thick silicon (Si) pad sensors and will sustain 1-MeV neutron equivalent fluences up to about 10\textasciicircum 16 neqcm\textasciicircum \textbraceleft -2\textbraceright . Campaigns have been underway to determine the level of degradation expected over the full life of the detector. A first study of irradiated test diode samples from 8-inch and 6-inch wafers at -30 \textdegree C is presented, including all three thicknesses and both bulk polarities. The electrical and charge collection properties are characterized after irradiation by current-voltage, capacitance-voltage and infrared Transient Current Technique measurements for sensors exposed to various fluence levels.   

Live

The all-silicon design of the tracking system of the CMS experiment provided excellent resolution for charged tracks and an efficient tagging of jets during Run1 and Run2 of LHC. The tracker consists of 15148 silicon strip and 1856 silicon pixel modules. The positions and orientations of the tracker module need to be determined with a precision of a few micrometers and are derived from reconstructed tracks of the collisions and cosmic ray data. The geometries are carefully validated with data-driven methods. We study possible systematic deformation introduced in the CMS tracker alignment and provide prescriptions for setting limits on those in analysis of the data. Nine first-order deformations natural for the cylindrical geometry of the CMS tracker are introduced. We determine constraints on these systematic misalignments by examining the effects of misalignment in simulated Monte Carlo samples and then comparing to collision and cosmic track data.   

Live

Accurately reconstructing and calibrating the particles we measure is essential to any ATLAS analysis. Due to both detector limitations and decay process complications, the energy measured by the detector is not always the true energy of a particle. One specific particle that requires extra attention to calibrate correctly is the tau lepton. The algorithms used to reconstruct taus rely on the calorimeter clusters and the track momenta associated to the tau candidate. Due to the existence of both charged and neutral pions in the final state of a tau decay, which can overlap in the calorimeter, and various other factors, the tau energy scale is challenging to calculate. While the offline energy scale determination can use information from both the ATLAS calorimeter and tracker as inputs to a Boosted Regression Tree (BRT) algorithm, such an implementation at the trigger level is particularly difficult, where ongoing studies have been attempting to include track information into the training of the BRT. Initial results show improvements in energy calibration for high momentum taus and potential application of this method in the trigger for the HL-LHC.   

Live

The electromagnetic calorimeter (ECAL) of the CMS detector is a homogenous, scintillating, lead tungstate crystal calorimeter, designed to achieve excellent energy resolution. Precise calibration of the CMS ECAL is crucial for maintaining the excellent performance required for many physics analyses. The energy response of the CMS ECAL has been precisely calibrated exploiting the full Run2 (2015-18) data. A dedicated calibration of each detector channel has been performed with physics events exploiting electrons from W and Z boson decays, photons from $\pi^0$/$\eta$ decays, and from the azimuthally symmetric energy distribution of minimum bias events. A special effort has been made to precisely calibrate the very forward region ($|\eta| > 2.5$) of the ECAL where the crystal transparency is extremely low. This region is crucial for jet and transverse missing energy reconstruction and dedicated algorithms are developed to monitor this region during the LHC Run3 (2021-24). We present the calibration strategies that have been implemented and the resulting performance achieved by ECAL for LHC Run 2. The procedures being developed to monitor and correct the response of channels in the very forward regions of ECAL during LHC Run 3 will be described in detail.   

On Demand

The hadronic part of the CMS endcap's high granularity calorimeter (HGCAL) upgrade will include 240,000 scintillating tiles, each read out by a silicon photomultipler (SiPM) mounted on a circuit board known as a tileboard. This talk presents an automated SiPM calibration system to characterize the SiPMs after installation on tileboards but before scintillating tiles are installed. Our calibration system uses a 3D gantry to suspend a sub-nanosecond fast-pulsing light source directly above each SiPM mounted on HGCal tileboards. Vertical motion of the gantry controls the light intensity on the SiPMs through the inverse square law, over the 4 orders of magnitude that is the expected dynamic range of the HGCAL SiPMs. This allows the calibration system to measure both low-light noise and performance parameters, and the nonlinear response over the dynamic range of SiPM operation. The estimated data collection rate is one minute per SiPM, allowing for the calibration of all SiPMs in HGCAL in $\sim$4,000 operation hours.   

On Demand

The LHC is planning an upgrade program which will smoothly bring the luminosity up to 5\texttimes 10\textasciicircum 34 cm-2 s-1, to possibly reach an integrated luminosity of 3000 fb-1 at the end of the next decade. This scenario, called the High Luminosity LHC (HL-LHC), will require an upgrade to the LHC detectors known as Phase-2 upgrade. The current CMS Outer Tracker will be replaced by a completely new device, in order to fully exploit the highly demanding operating conditions and the delivered luminosity. The new Tracker will also have trigger capabilities. To achieve these goals, R{\&}D activities are ongoing to develop solutions that would make this possible. In this presentation, some design choices for the CMS Outer Tracker upgrade are discussed along with some highlights of the assembly and testing developments.   

On Demand

The CMS electromagnetic calorimeter (ECAL) is made of about 75000 scintillating lead tungstate crystals arranged in a barrel and two endcaps. The scintillation light is read out by avalanche photodiodes in the barrel and vacuum phototriodes in the endcaps. Once read out, the scintillation pulse is amplified and sampled at 40 MHz by the on-detector electronics. The fast signal from the crystal scintillation enables energy as well as timing measurements from the data collected in proton-proton collisions with high energy electrons and photons. The stability of the timing measurement required to maintain the energy resolution is on the order of 1 ns. The single-channel time resolution of ECAL measured at beam tests for high energy showers is better than 100 ps. The timing resolution achieved with the data collected in proton-proton collisions at the LHC Run 2 is presented. The timing precision achieved is used in important physics measurements and also allows the study of subtle calorimetric effects, such as the timing response of different crystals belonging to the same electromagnetic shower. In addition, we present prospects for Run 3 and for the high luminosity phase of the LHC. It is speculated that time information could be exploited for pileup mitigation and for the assignment of the collision vertex for photons. In this respect, a detailed understanding of the time performance and of the limiting factors in time resolution will be important.