SiPM-on-Tile Modules for the CMS High Granularity Calorimeter

For the HL-LHC phase, the calorimeter end-cap of the CMS detector will be upgraded with a High Granularity Calorimeter (HGCAL) with increased transverse and longitudinal granularity to cope with the expected pileup and radiation. In regions where radiation levels allow, the hadronic calorimeter will use scintillator tiles coupled to silicon photomultipliers (SiPM-on-tiles) as active materials. The HGCAL Tilemodule is the basic detector module of this region and can hold up to 144 SiPM-on-tile channels and two readout electronic chips (HGCROCs). Performances of various SiPM-on-tiles, including different SiPM sizes, tile sizes, scintillator materials, production technologies and irradiated SiPMs, were quantified at beam tests using \SI{3}{GeV} electron beams at DESY-II. Further tests were conducted in temperature-controlled chambers to quantify the relationship between noise and leakage current passing through irradiated SiPMs on Tilemodules. The results from these tests were used in a model to obtain estimates of the signal-to-noise ratio (SNR) at the detector's end-of-life. Based on the estimates, changes to the final scintillator layout are proposed to obtain SNR>3 throughout the detector, including using smaller scintillator tiles in the frontmost layers and increasing the use of SiPMs with 3 \times \SI{3}{mm²} active area in the detector

Effect of the Decrease in Luminance Noise Range on Color Discrimination of Dichromats and Trichromats

Color vision assessment can be done using pseudoisochromatic stimuli, which has a luminance noise to eliminate brightness differences between the target and background of the stimulus. It is not clear the influence of the luminance noise on color discrimination. We investigated the effect of change in the luminance noise limits on color discrimination. Eighteen trichromats and ten congenital dichromats (eight protans, two deutans) had their color vision evaluated by the Cambridge Colour Test, and were genetically tested for diagnostic confirmation. The stimuli were composed of a mosaic of circles in a 5° circular field. A subset of the circles differed in chromaticity from the remaining field, forming a letter C. Color discrimination was estimated in stimulus conditions differing in luminance noise range: (i) 6–20 cd/m2; (ii) 8–18 cd/m2; (iii) 10–16 cd/m2; and (iv) 12–14 cd/m2. Six equidistant luminance values were used within the luminance noise limits with the mean stimulus luminance maintained constant under all conditions. A four-alternative, forced-choice method was applied to feed a staircase procedure to estimate color discrimination thresholds along eight chromatic axes. An ellipse model was adjusted to the eight color discrimination thresholds. The parameters of performance were threshold vector lengths and the ellipse area. Results were compared using the Kruskal-Wallis test with a significance level of 5%. The linear function model was applied to analyze the dependence of the discrimination parameters on the noise luminance limits. The first derivative of linear function was used as an indicator of the rate of change in color discrimination as a function of luminance noise changes. The rate of change of the ellipse area as a function of the luminance range in dichromats was higher than in trichromats (p < 0.05). Significant difference was also found for individual thresholds in half of the axes we tested. Luminance noise had a greater effect on color discrimination ability of dichromats than the trichromats, especially when the chromaticities were close to their protan and deutan color confusion lines

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

Peer reviewe

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

The SiPM-on-Tile Section of the CMS High Granularity Calorimeter

For the high luminosity LHC (HL-LHC) phase, the calorimeter end-cap of the CMS detector will be upgraded with a High Granularity Calorimeter (HGCAL). This sampling calorimeter will use silicon sensors and scintillator tiles read out by silicon photomultipliers (SiPMs) as active material (SiPM-on-tile). The complete HGCAL will be operated at $-30^\circ$C. The primary detector module in the SiPM-on-tile section is the tile module, consisting of a PCB with one or two HGCAL Read Out Chips (HGCROC) ASICs, reading up to 144 SiPM-on-tiles. For geometric reasons, the tile modules and the tiles on the tile modules will increase in size with increasing radial distance from the beam pipe. Eight variations of tile modules have been designed to cover the total area of 370 m$^2$. This includes using two different SiPM sizes and 21 different tile sizes manufactured using two different materials. Production of tile modules for the upgrade is foreseen to start in 2024. An overview of the current status and production plans of the SiPM-on-tile section will be presented in this contribution

Pulse Shape Characterization of Silicon Diodes for HGCal with data from Beam Test at CERN

The High Luminosity phase of the LHC (starting operation in 2025) will provide unprecedented instantaneous and integrated luminosity, with 25 ns bunch crossing intervals and up to 140 pileup events. A challenge is to provide excellent physics performance in such a harsh environment to fully exploit the HL-LHC potentialities and explore new physics frontiers. In this context, the High Granularity Calorimeter is the detector designed to provide electromagnetic and hadronic energy coverage and reconstruction in the forward direction of the upgraded CMS. In April 2016 and June 2016, a set of 36 diodes were tested in order to understand various characteristics of its performance, in order to use them in the upgraded HG Calorimeter. Here, the silicon diodes were mounted onto a test bench at CERN’s beam test area and exposed to electron showers. Data received from these diodes were acquired and analysed separately. The objective of this report is to show the variation of Time Rise, Time Over Threshold with various parameters such as Signal over Noise Ratio, Irradiation level and Thickness. Time Rise is defined as the time it takes by the signal to increase its intensity from 10% its peak intensity to 90% its peak intensity value. The Time Over Threshold here is defined as the time the signal spends over 50% of its peak intensity value

Beam Tests of the First CMS HGCAL Tileboard Prototypes

For the HL-LHC phase, the calorimeter endcap of the CMS detector will be upgraded with a High Granularity Calorimeter (HGCAL), a sampling calorimeter which will use silicon sensors as well as scintillator tiles read out by silicon photomultipliers (SiPMs) as active material (SiPM-on-tile). The complete HGCAL will be operated at -30 degC. The SiPMs will be used in areas where the expected radiation dose during the lifetime of the detector is up to 5*10^13 neq/cm^2. The design of the SiPM-on-tile part is inspired by the CALICE AHCAL.The basic detector unit in the SiPM-on-tile part is the tilemodule, consisting of a PCB with one or two HGCROC ASICs, reading out up to 96 tiles with SiPMs. The first functional tilemodule prototypes have been constructed with HGCROC2 ASICs and SiPMs which are candidates for the HGCAL production. They have undergone beam tests at DESY and Fermilab, investigating the interplay of the components and evaluating the performance with several scintillator tile types. First test were also performed with irradiated SiPMs. We will report on these tests, which were all performed in 2020, and the work still to come using beams

Evaluation of the Performance ofSiPM-on-Tiles at the End of Lifeof the CMS HGCAL Upgrade

For the HL-LHC phase, the calorimeter endcap of the CMS detector will be upgraded with a High Granularity Calorimeter (HGCAL), a sampling calorimeter that will use silicon sensors as well as scintillator tiles read out by silicon photomultipliers (SiPMs) as active material (SiPM-on-tile). The design of the SiPM-on-tile section was inspired by the CALICE AHCAL. The complete HGCAL will be operated at −30∘C.The basic detector unit in the SiPM-on-tile section is the tile module, consisting of a PCB with one or two HGCROC ASICs, reading out up to 96 SiPM-on-tiles. Signals from MIPs passing through the SiPM-on-tiles are used to quantify the performance of SiPM-on-tiles. With irradiation, their performance degrades while increasing the noise. The ratio between the MIP signal and noise is known as the signal-to-noise ratio (SNR). In order to maintain an SNR>3 at end of the detector lifetime, SiPMs will be used in areas where the expected radiation dose during the lifetime of the detector is less than 5× 1013 neq/cm2.A series of tests were conducted to quantify the performance of SiPM-on-tiles mounted on tile modules including beam tests and cold tests at −30∘C. These tests were also repeated using irradiated SiPMs mounted on the tile modules. These tests were then used to extrapolate the performance expectations at the detector’s end of life

Latest Tests of the CMS HGCAL Tileboard Prototypes

For the HL-LHC phase, the calorimeter endcap of the CMS detector will be upgraded with a High Granularity Calorimeter (HGCAL), a sampling calorimeter that will use silicon sensors as well as scintillator tiles read out by silicon photomultipliers (SiPMs) as active material (SiPM-on-tile). The complete HGCAL will be operated at −30∘C. The SiPMs will be used in areas where the expected radiation dose during the lifetime of the detector is up to 5×1013 neq/cm2. The basic detector unit in the SiPM-on-tile part is the tile module, consisting of a PCB with one or two HGCROC ASICs, reading out up to 96 tiles with SiPMs. The design of the SiPM-on-tile part is inspired by the CALICE AHCAL.In the calorimeter, the response of each SiPM-on-tile on the energy scale will be calibrated using the MIP signal. This is compromised by radiation damage decreasing the scintillator light output and increasing the SiPM dark current-induced noise. SiPM irradiation tests provide data on the current increase as a function of accumulated neutron fluence. From this increase in current, the increase in noise for a fixed SiPM bias voltage can be predicted. Tests were conducted on SiPMs irradiated to 2×1012 neq/cm2 mounted on a tileboard, at temperatures ranging between −30∘C and +30∘C using a climate chamber. Results from these tests will be reported