3D silicon pixel detectors for the ATLAS Forward Physics experiment

The ATLAS Forward Physics (AFP) project plans to install 3D silicon pixel detectors about 210 m away from the interaction point and very close to the beamline (2-3 mm). This implies the need of slim edges of about 100-200 $\mu$m width for the sensor side facing the beam to minimise the dead area. Another challenge is an expected non-uniform irradiation of the pixel sensors. It is studied if these requirements can be met using slightly-modified FE-I4 3D pixel sensors from the ATLAS Insertable B-Layer production. AFP-compatible slim edges are obtained with a simple diamond-saw cut. Electrical characterisations and beam tests are carried out and no detrimental impact on the leakage current and hit efficiency is observed. For devices without a 3D guard ring a remaining insensitive edge of less than 15 $\mu$m width is found. Moreover, 3D detectors are non-uniformly irradiated up to fluences of several 10$^{15}$ n$_{eq}$/cm$^2$ with either a focussed 23 GeV proton beam or a 23 MeV proton beam through holes in Al masks. The efficiency in the irradiated region is found to be similar to the one in the non-irradiated region and exceeds 97% in case of favourable chip-parameter settings. Only in a narrow transition area at the edge of the hole in the Al mask, a significantly lower efficiency is seen. A follow-up study of this effect using arrays of small pad diodes for position-resolved dosimetry via the leakage current is carried out.Comment: 10 pages, submitted to JINS

Studies of irradiated AMS H35 CMOS detectors for the ATLAS tracker upgrade

Silicon detectors based on the HV-CMOS technology are being investigated as possible candidate for the outer layers of the ATLAS pixel detector for the High Luminosity LHC. In this framework the H35Demo ASIC has been produced in the 350 nm AMS technology (H35). The H35Demo chip has a large area ($18.49 \times 24.40 \, \mathrm{mm^2}$) and includes four different pixel matrices and three test structures. In this paper the radiation hardness properties, in particular the evolution of the depletion region with fluence is studied using edge-TCT on test structures. Measurements on the test structures from chips with different substrate resistivity are shown for non irradiated and irradiated devices up to a cumulative fluence of $2 \cdot 10^{15} \, \mathrm{1\,MeV\, n_{eq} / cm^{2}}$

Towards the discovery of new physics with lepton-universality ratios of b→sℓℓ decays

Tests of lepton-universality as rate ratios in $b\to s \ell\ell$ transitions can be predicted very accurately in the Standard Model. The deficits with respect to expectations reported by the LHCb experiment in muon-to-electron ratios of the $B\to K^{(*)}\ell\ell$ decay rates thus point to genuine manifestations of lepton non-universal new physics. In this paper, we analyse these measurements in the context of effective field theory. First, we discuss the interplay of the different operators in $R_K$ and $R_{K^*}$ and provide predictions for $R_{K^*}$ in the Standard Model and in new-physics scenarios that can explain $R_K$. We also provide approximate numerical formulas for these observables in bins of interest as functions of the relevant Wilson coefficients. Secondly, we perform frequentist fits to $R_{K}$ and $R_{K^*}$. The SM disagrees with these measurements at $3.7\sigma$ significance. We find excellent fits in scenarios with combinations of $\mathcal O_{9(10)}^\ell=\bar s\gamma^\mu b_L~\ell\gamma_\mu(\gamma_5) \ell$ operators, with pulls relative to the Standard Model in the region of $4\sigma$. An important conclusion of our analysis is that a lepton-specific contribution to $\mathcal O_{10}$ is essential to understand the data. Under the hypothesis that new-physics couples selectively to the muons, we also present fits to other $b\to s\mu\mu$ data with a conservative error assessment, and comment on more general scenarios. Finally, we discuss new lepton universality ratios that, if new physics is the origin of the observed discrepancy, should contribute to the statistically significant discovery of new physics in the near future.Comment: Matches published versio

Radiation hard Depleted Monolithic Active Pixel Sensors with high-resistivity substrates

High Voltage/High resistivity Depleted Monolithic Active Pixel Sensors (HV/HR-DMAPS) is a technology which is becoming of great interest for high energy physics applications.With respect to hybrid pixel detectors the monolithic approach offers the main advantages of reduced material budget and production costs due to the absence of the bump bonding process. This aspect is important especially when large areas need to be covered as in the tracking detectors of the LHC experiments. Thus, the possibility of employing this technology in the outermost layers of the upgraded ATLAS pixel detector at the HL-LHC is being investigated.Different HR/HV-DMAPS prototypes have been recently developed for the future ATLAS Inner Tracker (ITk) with the aim of studying their radiation hardness and the feasibility of producing large area devices.The H35DEMO is a large area demonstrator chip for the ITk designed by KIT, IFAE and University of Liverpool and produced in AMS 350 nm HV-CMOS technology with an engineering run on four different substrate resistivities: 20, 80, 200 and 1000 $\mathrm{\Omega cm}$. It consists of four large matrices, two of which include digital electronics and are thus fully monolithic. One, called CMOS matrix, has comparators made of CMOS transistors in the periphery only, while the other, called NMOS matrix, includes also comparators made of NMOS transistors directly in the pixels. The other two matrices have only analog front-end electronics and are meant to be coupled to ATLAS FE-I4 chips. All matrices feature pixels with a size of $\mathrm{(50\times250)\;\mu m^2}$ in which the analog electronics are embedded in a Deep N-WELL (DNWELL) also acting as collecting electrode.A Data Acquisition (DAQ) system was developed at IFAE to read out and test the monolithic matrices of the H35DEMO both in the laboratory and with beam test experiments. H35DEMO chips with a resistivity of 200 $\mathrm{\Omega cm}$ have been irradiated with reactor neutrons to a particle fluence of $1\times10^{15}$ $\mathrm{1\;MeV\;n_{eq}/cm^2}$, the expected fluence for the outermost pixel layer of ITk. The monolithic CMOS matrix of the H35DEMO chip was extensively characterised before and after irradiation in beam tests at Fermilab and DESY, with proton and electron beams, respectively.Results after irradiation show good performance in terms of hit efficiency with thresholds of about 1800 e and a bias voltage of 150 V.Another production of monolithic HV-CMOS prototypes in LFoundry 150 nm technology (LF2) has been recently completed. It includes sensors with a similar DNWELL concept as the H35DEMO but with a smaller pixel size of $\mathrm{(50\times50)\;\mu m^2}$. Preliminary measurements of leakage current of the LF2 chips have been preformed showing good agreement with what expected from the foundry process

Overview of CNM LGAD results: Boron Si-on-Si and epitaxial wafers

Low Gain Avalanche Detectors (LGADs) are n-on-p silicon sensors with an extra p-layer below the collection electrode which provides signal amplification. When the primary electrons reach the amplification region new electron-hole pairs are created that enhance the generated signal. The moderate gain of these sensors, together with the relatively thin active region, provide precise time information for minimum ionizing particles. To mitigate the effect of pile-up at the HL-LHC the ATLAS and CMS experiments have chosen the LGAD technology for the High Granularity Timing Detector (HGTD) and for the End-Cap Timing Layer (ETL), respectively. A full characterization of recent productions of LGAD sensors fabricated at CNM has been carried out before and after neutron irradiation up to 2.5 $\times$ 10$^{15}$ n$_{eq}$/cm$^{2}$ . Boron-doped sensors produced in epitaxial and Si-on-Si wafers have been studied. The results include their electrically characterization (IV and bias voltage stability) and performance studies (charge and time resolution) for single pad devices with a Sr-90 radioactive source set-up. The behaviour of the Inter-Pad region for irradiated 2 $\times$ 2 LGAD arrays, using the Transient Current Technique (TCT), is shown. The results indicate that the Si-on-Si devices with higher resistivity perform better than the epitaxial ones

Transcriptionally active HERV-H retrotransposons demarcate topologically associating domains in human pluripotent stem cells.

Chromatin architecture has been implicated in cell type-specific gene regulatory programs, yet how chromatin remodels during development remains to be fully elucidated. Here, by interrogating chromatin reorganization during human pluripotent stem cell (hPSC) differentiation, we discover a role for the primate-specific endogenous retrotransposon human endogenous retrovirus subfamily H (HERV-H) in creating topologically associating domains (TADs) in hPSCs. Deleting these HERV-H elements eliminates their corresponding TAD boundaries and reduces the transcription of upstream genes, while de novo insertion of HERV-H elements can introduce new TAD boundaries. The ability of HERV-H to create TAD boundaries depends on high transcription, as transcriptional repression of HERV-H elements prevents the formation of boundaries. This ability is not limited to hPSCs, as these actively transcribed HERV-H elements and their corresponding TAD boundaries also appear in pluripotent stem cells from other hominids but not in more distantly related species lacking HERV-H elements. Overall, our results provide direct evidence for retrotransposons in actively shaping cell type- and species-specific chromatin architecture

Implications of new evidence for lepton-universality violation in b →sℓ+ℓ- decays

Motivated by renewed evidence for new physics in b→sℓℓ transitions in the form of LHCb's new measurements of theoretically clean lepton-universality ratios and the purely leptonic Bs→μ+μ- decay, we quantify the combined level of discrepancy with the Standard Model and fit values of short-distance Wilson coefficients. A combination of the clean observables RK, RK∗, and Bs→μμ alone results in a discrepancy with the Standard Model at 4.0σ, up from 3.5σ in 2017. One-parameter scenarios with purely left-handed or with purely axial coupling to muons fit the data well and result in a ∼5σ pull from the Standard Model. In a two-parameter fit of new-physics contributions with both vector and axial-vector couplings to muons the allowed region is much more restricted than in 2017, principally due to the much more precise result on Bs→μ+μ-, which probes the axial coupling to muons. Including angular observables data restricts the allowed region further. A by-product of our analysis is an updated average of BR(Bs→μ+μ-)=(2.8±0.3)×10-9

Разработка эффективных центраторов обсадной колонны

Основной целью работы является разработка эффективных центраторов обсадной колонны. Для выполнения поставленной цели рассмотрены основные решаемые задачи: 1 Провести обзор сортамента центраторов обсадных колонн различных производителей. 2 Провести патентный обзор центраторов обсадных колонн. 3 Провести анализ, существующих центраторов и разработать эффективный центратор обсадной колонны, лишенный недостатков, выделенных в анализе. Также выполнены разделы "Социальная ответственность" и "Производственный менеджмент, ресурсоэффективность и ресурсосбережение".The main goal of the work is to develop efficient casing centralizers. To accomplish this goal, the main tasks are addressed: 1 Review the range of casing centralizers from different manufacturers. 2 Conduct a patent review of casing centralizers. 3 Carry out an analysis of existing centralizers and develop an effective casing centering device that is free from the weaknesses highlighted in the analysis. Also the sections "Social Responsibility" and "Production Management, Resource Efficiency and Resource Saving"

3D active edge silicon sensors: Device processing, yield and QA for the ATLAS-IBL production

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