arXiv subjects

Aashaq Shah

Publications and source records attributed to Aashaq Shah.

11 recordsLinked to original sources

arXiv2026

Calibration and Performance of proANUBIS: A proof-of-concept detector for the ANUBIS experiment

Long-lived particles with lifetimes $τ>10$~ps are predicted by many extensions of the Standard Model with viable dark matter candidates. The ANUBIS experiment proposes to extend the experimental sensitivity to long-lived particles by instrumenting the ceiling of the ATLAS cavern with Resistive Plate Chamber detectors in order to reconstruct vertices from long-lived particle decays in the air-filled volume above the ATLAS detector. The proANUBIS detector has been installed in the ATLAS cavern to validate the detector technology planned for ANUBIS and to take in-situ measurements of muon and hadron fluxes inside the ATLAS cavern using $pp$ collision data from the LHC. In this paper, the data collected, reconstruction techniques used, and performance of the \proanubis detector are discussed. The detection efficiency and timing resolution are found to be consistent with expectations and to meet the performance requirements of ANUBIS.

hep-ex↗

arXiv2025

Commissioning of proANUBIS: A proof-of-concept detector for the ANUBIS experiment

Long-lived particles (LLPs), predicted by various extensions of the Standard Model (SM), have become a key focus of the contemporary search programme for physics beyond the SM. To enhance LLP discovery potential at the LHC, the ANUBIS experiment has been proposed to instrument the ceiling of the ATLAS experiment's underground cavern with dedicated tracking detectors. This report summarises recent progress towards realising ANUBIS. Specifically, a key milestone has been achieved with the installation and commissioning of proANUBIS, a prototype that serves as a proof-of-concept for ANUBIS. We describe the proANUBIS setup, including its remotely-operated data acquisition system and automatic signal processing chain. The proANUBIS demonstrator is used to evaluate the detector performance under realistic conditions in the UX1 ATLAS experimental cavern, including readout synchronisation with the ATLAS experiment. Furthermore, proANUBIS allows for the direct measurement of relevant background processes in a representative location within the ATLAS cavern, providing input for the simulation of such processes for the future ANUBIS detector. The paper concludes with an update on the current status of the ANUBIS project and its roadmap toward a full-scale implementation in the ATLAS cavern.

hep-ex↗

arXiv2025

Construction of proANUBIS: A proof-of-concept detector for the ANUBIS experiment

The ANUBIS experiment aims to search for long-lived particles at the Large Hadron Collider (LHC) at CERN. To assess the feasibility of the project, a prototype detector, proANUBIS, was designed, constructed, and prepared for installation in the UX1 ATLAS experimental cavern at the LHC. The primary physics goals of proANUBIS are to determine the technical limitations of the detector technology and to explore the ANUBIS detector concept through in-situ measurements of muon and hadron fluxes inside the ATLAS cavern, which can be used to refine Monte Carlo simulations of such fluxes further. This report describes the design and construction of the proANUBIS experimental setup using Resistive Plate Chambers (RPCs), highlighting the possible future use case of the technology for ANUBIS. Details on the RPC technology, construction processes, quality control measures, and performance studies are discussed. Furthermore, the RPC front-end on-detector electronics and data acquisition components of proANUBIS are presented.

hep-ex↗

arXiv2025

Quality assurance tests and techniques to investigate and improve hermeticity of ATLAS Phase II Resistive Plate Chamber detectors

The Phase II upgrade of the ATLAS Muon Spectrometer will involve the installation of approximately 1000 next-generation Resistive Plate Chamber (RPC) singlets. This upgrade aims to enhance detector coverage, increase hit efficiency, and improve timing precision, ultimately strengthening the precision and robustness of the muon trigger system. The upgrade is essential for maintaining the performance of the muon spectrometer in the high-luminosity environment of the HL-LHC, where increased radiation and event rates pose significant challenges. Currently, detector production is underway, with gas gaps being commercially produced in Italy. To ensure the integrity of these gas gaps, especially their mechanical properties and gas tightness, several investigative techniques have been proposed and implemented. This study discusses the results of Thermal Cycling tests performed on ATLAS RPC gas gaps. These tests were conducted between $-33^{\circ}$C and $+35^{\circ}$C in a climate room at University of Cambridge and $-20^{\circ}$C and $+30^{\circ}$C in laboratories at INFN Frascati, providing insights into the effects of mechanical stress due to thermal expansion on gas leaks. Additionally, it outlines various methods employed to assess and enhance the gas tightness of the detectors. The ultimate objective is to produce hermetic RPC detectors, minimising the emission of environmentally harmful gases and mitigating their impact on global warming.

physics.ins-det↗

arXiv2025

Performance studies of thin gas gap Resistive Plate Chamber prototypes with low Global Warming Potential gases for the ANUBIS experiment

Resistive Plate Chambers (RPCs) have traditionally operated with high Global Warming Potential (GWP) gas mixtures, adding to the environmental footprint of large-scale physics experiments. In response, efforts are underway to explore environmentally friendly alternatives as a long-term solution and low-GWP as a feasible short- to medium-term replacement for standard RPC gases. This study tests a few mixtures in 50 cm $\times$ 50 cm, 1 mm single-gap High-Pressure Laminate (HPL) RPC prototypes, as part of ongoing efforts for the ANUBIS experiment, which will operate with a 9.8 m$^{3}$ active gas volume. Measurements of performance metrics, including current and efficiency, are conducted with both standard and modified mixtures to assess their viability in sustaining detector performance. The results are also relevant for large RPC systems in other experiments at the LHC, such as ATLAS and CMS, as well as in applications beyond the LHC, supporting a shift toward environmentally sustainable gas mixtures in particle physics detectors.

physics.ins-det↗

arXiv2024

Searches for long-lived particles with the ANUBIS experiment

In recent years, there has been growing interest in the search for long-lived particles (LLPs), as predicted by various extensions of the Standard Model (SM). The AN Underground Belayed In-Shaft search experiment (ANUBIS) was proposed to search for such particles by instrumenting CERN's ATLAS underground cavern with tracking detectors. This report provides an overview of the current efforts to realize the ANUBIS project focusing on the latest optimized detector geometry and the installation of proANUBIS -- a prototype or proof-of-concept demonstrator. The latter aims to offer insights into anticipated backgrounds for the ANUBIS experiment and demonstrate the feasibility of such a project. The ongoing efforts are needed to contribute to the continuous optimization and development of the ANUBIS project.

hep-ex↗

arXiv2024

Installation of proANUBIS -- a proof-of-concept demonstrator for the ANUBIS experiment

AN Underground Belayed In-Shaft search experiment (ANUBIS) was proposed to search for neutral long-lived particles (LLPs) at CERN's ATLAS underground cavern. A prototype or a proof-of-concept demonstrator detector - proANUBIS was recently installed to prove the feasibility of such an experiment. The prototype demonstrator is expected to play a role in validating simulation studies and providing insights into the anticipated backgrounds for the ANUBIS experiment. The current report provides an overview of the experimental setup for this prototype detector, and its commissioning and installation details.

hep-ex↗

arXiv2018

Layout and Assembly Technique of the GEM Chambers for the Upgrade of the CMS First Muon Endcap Station

Triple-GEM detector technology was recently selected by CMS for a part of the upgrade of its forward muon detector system as GEM detectors provide a stable operation in the high radiation environment expected during the future High-Luminosity phase of the Large Hadron Collider (HL-LHC). In a first step, GEM chambers (detectors) will be installed in the innermost muon endcap station in the $1.6<\left|η\right|<2.2$ pseudo-rapidity region, mainly to control level-1 muon trigger rates after the second LHC Long Shutdown. These new chambers will add redundancy to the muon system in the $η$-region where the background rates are high, and the bending of the muon trajectories due to the CMS magnetic field is small. A novel construction technique for such chambers has been developed in such a way where foils are mounted onto a single stack and then uniformly stretched mechanically, avoiding the use of spacers and glue inside the active gas volume. We describe the layout, the stretching mechanism and the overall assembly technique of such GEM chambers.

physics.ins-det↗

arXiv2018

Impact of Single-Mask Hole Asymmetry on the Properties of GEM Detectors

A single-mask Gas Electron Multiplier (GEM) technique overcomes the cumbersome practice of alignment of two masks and allows the production of foils with very large area as needed for the CMS muon forward region upgrade. However, the holes obtained with refinements in the single-mask technique are asymmetrically bi-conical in shape compared to symmetrically bi-conical holes of double-mask technology. The hole geometry and their uniformity define the performance of the detectors which are constructed with such GEM foils. To evaluate the effect of this asymmetry, the foils have been characterized experimentally using a special prototype with three single-mask GEM foils. The structure allowed to change the orientation of foils, testing from above with foils having a large hole opening, testing from the bottom with all the foils having small hole opening. The effective gain, energy resolution and the charging up behavior are compared for the two different hole orientations.

physics.ins-det↗

arXiv2018

Performance of the triple GEM detector built using commercially manufactured GEM foils in India

The Gas Electron Multiplier (GEM) detectors has been utilized for various applications due to their excellent spatial resolution, high rate capabilities and flexibility in design. The GEM detectors stand as a promising device to be used in nuclear and particle physics experiments. Many future experiments and upgrades are looking forward to use this technology leading to high demand of GEM foils. Until now, CERN is the only reliable manufacturer and distributor of GEM foils, but with technology transfer, few other industries across the globe have started manufacturing these foils employing the same photo-lithographic technique. The Micropack Pvt. Ltd. is one such industry in India which produced first few $10~cm ~\times~ 10~cm$ GEM foils, which were then distributed to few collaborating partners for testing reliability and performance of foils before they can be accepted by the scientific community. Characterization of three such foils have already been performed by studying their optical and electrical properties. Using these foils a triple GEM detector has been built and various performance characteristics have been measured. In this paper, we specifically report measurements on gain, resolution and response uniformity, by utilizing local quality control set-ups existing at University of Delhi.

physics.ins-det↗

arXiv2018

Development, Characterization and Qualification of first GEM foils produced in India

The increasing demand for Gas Electron Multiplier (GEM) foils has been driven by their application in many current and proposed high-energy physics experiments. Micropack, a Bengaluru-based company, has established and commercialized GEM foils for the first time in India. Micropack used the double-mask etching technique to successfully produce 10 cm $\times$ 10 cm GEM foil. In this paper, we report on the development as well as the geometrical and electrical properties of these foils, including the size uniformity of the holes and leakage current measurements. Our characterization studies show that the foils are of good quality and satisfy all the necessary quality control criteria.

physics.ins-det↗