arXiv subjects

E. Oliveri

Publications and source records attributed to E. Oliveri.

At least 37 records · Page 2Linked to original sources

arXiv2024

Spatial resolution studies using point spread function extraction in optically read out Micromegas and GEM detectors

Optically read out gaseous detectors are used in track reconstruction and imaging applications requiring high granularity images. Among resolution-determining factors, the amplification stage plays a crucial role and optimisations of detector geometry are pursued to maximise spatial resolution. To compare MicroPattern Gaseous Detector (MPGD) technologies, focused low-energy X-ray beams at the SOLEIL synchrotron facility were used to record and extract point spread function widths with Micromegas and GEM detectors. Point spread function width of $\approx$108\,\microns for Micromegas and $\approx$127\,\microns for GEM foils were extracted. The scanning of the beam with different intensities, energies and across the detector active region can be used to quantify resolution-limiting factors and improve imaging detectors using MPGD amplification stages.

physics.ins-det↗

arXiv2024

Single channel PICOSEC Micromegas detector with improved time resolution

This paper presents design guidelines and experimental verification of a single-channel PICOSEC Micromegas (MM) detector with an improved time resolution. The design encompasses the detector board, vessel, auxiliary mechanical parts, and electrical connectivity for high voltage (HV) and signals, focusing on improving stability, reducing noise, and ensuring signal integrity to optimize timing performance. A notable feature is the simple and fast reassembly procedure, facilitating quick replacement of detector internal components that allows for an efficient measurement strategy involving different detector components. The paper also examines the influence of parasitics on the output signal integrity. To validate the design, a prototype assembly and three interchangeable detector boards with varying readout pad diameters were manufactured. The detectors were initially tested in the laboratory environment. Finally, the timing performance of detectors with different pad sizes was verified using a Minimum Ionizing Particle (MIP) beam test. Notably, a record time resolution for a PICOSEC Micromegas detector technology with a CsI photocathode of 12.5$\pm$0.8 ps was achieved with a 10 mm diameter readout pad size detector.

physics.ins-det↗

arXiv2024

Spatial resolution improvements with finer-pitch GEMs

Gas Electron Multipliers (GEMs) are used in many particle physics experiments, employing their 'standard' configuration with amplification holes of 140 um pitch in a hexagonal pattern. However, the collection of the charge cloud from the primary ionisation electrons from the drift region of the detector into the GEM holes affects the position information from the initial interacting particle. In this paper, the results from studies with a triple-GEM detector with an X-Y-strip readout anode are presented. It is demonstrated that GEMs with a finer hole pitch of here 90 um improve the detector's spatial resolution. Within these studies, also the impact of the front-end electronics on the spatial resolution was investigated, which is briefly discussed in the paper.

physics.ins-det↗

arXiv2024

Characterisation of resistive MPGDs with 2D readout

Micro-Pattern Gaseous Detectors (MPGDs) with resistive anode planes provide intrinsic discharge robustness while maintaining good spatial and time resolutions. Typically read out with 1D strips or pad structures, here the characterisation results of resistive anode plane MPGDs with 2D strip readout are presented. A uRWELL prototype is investigated in view of its use as a reference tracking detector in a future gaseous beam telescope. A MicroMegas prototype with a fine-pitch mesh (730 line-pairs-per-inch) is investigated, both for comparison and to profit from the better field uniformity and thus the ability to operate the detector more stable at high gains. Furthermore, the measurements are another application of the RD51 VMM3a/SRS electronics.

physics.ins-det↗

arXiv2023

Observation of strong wavelength-shifting in the argon-tetrafluoromethane system

We report the scintillation spectra of Ar-CF$_4$ mixtures in the range 210-800~nm, obtained under X-ray irradiation for various pressures (1-5~bar) and concentrations (0-100%). Special care was taken to eliminate effects related to space charge and recombination, so that results can be extrapolated following conventional wisdom to those expected for minimum ionizing particles under the typical electric fields employed in gaseous instrumentation. Our study sheds light into the microscopic pathways leading to scintillation in this family of mixtures.

physics.ins-det↗

arXiv2023

The MIGDAL experiment: Measuring a rare atomic process to aid the search for dark matter

We present the Migdal In Galactic Dark mAtter expLoration (MIGDAL) experiment aiming at the unambiguous observation and study of the so-called Migdal effect induced by fast-neutron scattering. It is hoped that this elusive atomic process can be exploited to enhance the reach of direct dark matter search experiments to lower masses, but it is still lacking experimental confirmation. Our goal is to detect the predicted atomic electron emission which is thought to accompany nuclear scattering with low, but calculable, probability, by deploying an Optical Time Projection Chamber filled with a low-pressure gas based on CF$_4$. Initially, pure CF$_4$ will be used, and then in mixtures containing other elements employed by leading dark matter search technologies -- including noble species, plus Si and Ge. High resolution track images generated by a Gas Electron Multiplier stack, together with timing information from scintillation and ionisation readout, will be used for 3D reconstruction of the characteristic event topology expected for this process -- an arrangement of two tracks sharing a common vertex, with one belonging to a Migdal electron and the other to a nuclear recoil. Different energy-loss rate distributions along both tracks will be used as a powerful discrimination tool against background events. In this article we present the design of the experiment, informed by extensive particle and track simulations and detailed estimations of signal and background rates. In pure CF$_4$ we expect to observe 8.9 (29.3) Migdal events per calendar day of exposure to an intense D-D (D-T) neutron generator beam at the NILE facility located at the Rutherford Appleton Laboratory (UK). With our nominal assumptions, 5$σ$ median discovery significance can be achieved in under one day with either generator.

hep-ex↗

arXiv2023

The novel XYU-GEM to resolve ambiguities

Removing ambiguities within a single stage becomes crucial when one can not use multiple detectors behind each other to resolve them which naturally is the case for neutral radiation. An example would be RICH detectors. Commonly pixilated readout is choosen for this purpose. However, this causes a remarkable increase in quantity of channels and does not scale up well. Therefore, the XYU-GEM was proposed as a three coordinate strip-readout which is combined with a triple GEM detector. The readout complements a common XY readout with an additional projection which is tilted by 45°. The overdetermination due to three projections can be used to resovle ambiguities. Following the detector design will be explained, first measurements discussed to understand the response of the detector and a way to change the charge sharing without changing the manufacturing parameters of the readout.

physics.ins-det↗

arXiv2023

X-ray imaging with Micromegas detectors with optical readout

In the last years, optical readout of Micromegas gaseous detectors has been achieved by implementing a Micromegas detector on a glass anode coupled to a CMOS camera. Effective X-ray radiography was demonstrated using integrated imaging approach. High granularity values have been reached for low-energy X-rays from radioactive sources and X-ray generators. Detector characterization with X-ray radiography has led to two applications: neutron imaging for non-destructive examination of highly gamma-ray emitting objects and beta imaging for the single cell activity tagging in the field of oncology drug studies. First measurements investigating the achievable spatial resolution of the glass Micromegas detector at the SOLEIL synchrotron facility with a high-intensity and flat irradiation field will be shown in this article.

physics.ins-det↗

arXiv2023

Demonstration of Gd-GEM detector design for neutron macromolecular crystallography applications

The European Spallation Source (ESS) in Lund, Sweden will become the world's most powerful thermal neutron source. The Macromolecular Diffractometer (NMX) at the ESS requires three 51.2 x 51.2~cm$^{2}$ detectors with reasonable detection efficiency, sub-mm spatial resolution, a narrow point spread function (PSF) and good time resolution. This work presents measurements with the improved version of the NMX detector prototype consisting of a Triple-GEM detector with natural Gd converter and a low material budget readout. The detector was successfully tested at the neutron reactor of the Budapest Neutron Centre (BNC) and at the D16 instrument at the Institut Laue-Langevin (ILL) in Grenoble. The measurements with Cadmium and Gadolinium masks in Budapest demonstrate that the point spread function of the detector lacks long tails that could impede the measurement of diffraction spot intensities. On the D16 instrument at ILL, diffraction spots from Triose phosphate isomerase w/ 2-phosphoglycolate (PGA) inhibitor were measured both in the D16 Helium-3 detector and the Gd-GEM. The comparison between the two detectors show a similar point spread function in both detectors, and the expected efficiency ratio compared to the Helium-3 detector. Both measurements together thus give good indications that the Gd-GEM detector fits the requirements for the NMX instrument at ESS.

physics.ins-det↗

arXiv2023

Performance of the new RD51 VMM3a/SRS beam telescope---studying MPGDs simultaneously in energy, space and time at high rates

The RD51 collaboration maintains a common infrastructure at CERN for its R & D activities, including two beam telescopes for test beam campaigns. Recently, one of the beam telescopes has been equipped and commissioned with new multi-channel and charge-sensitive front-end electronics based on the ATLAS/BNL VMM3a front-end ASIC and the RD51 Scalable Readout System (SRS). This allows to read out the detectors at high rates (up to the MHz regime) with electronics time resolutions of the order of 1 ns and the ability to handle different detector types and sizes, due to a larger dynamic range compared to the previous front-end electronics based on the APV25 ASIC. Having studied and improved the beam telescope's performance over the course of three test beam campaigns, the results are presented in this paper.

physics.ins-det↗

arXiv2022

Precise timing and recent advancements with segmented anode PICOSEC Micromegas prototypes

Timing information in current and future accelerator facilities is important for resolving objects (particle tracks, showers, etc.) in extreme large particles multiplicities on the detection systems. The PICOSEC Micromegas detector has demonstrated the ability to time 150\,GeV muons with a sub-25\,ps precision. Driven by detailed simulation studies and a phenomenological model which describes stochastically the dynamics of the signal formation, new PICOSEC designs were developed that significantly improve the timing performance of the detector. PICOSEC prototypes with reduced drift gap size ($\sim$\SI{119}{\micro\metre}) achieved a resolution of 45\,ps in timing single photons in laser beam tests (in comparison to 76\,ps of the standard PICOSEC detector). Towards large area detectors, multi-pad PICOSEC prototypes with segmented anodes has been developed and studied. Extensive tests in particle beams revealed that the multi-pad PICOSEC technology provides also very precise timing, even when the induced signal is shared among several neighbouring pads. Furthermore, new signal processing algorithms have been developed, which can be applied during data acquisition and provide real time, precise timing.

physics.ins-det↗

arXiv2022

Snowmass 2021 White Paper Instrumentation Frontier 05 -- White Paper 1: MPGDs: Recent advances and current R&D

This paper will review the origins, development, and examples of new versions of Micro-Pattern Gas Detectors. The goal for MPGD development was the creation of detectors that could cost-effectively cover large areas while offering excellent position and timing resolution, and the ability to operate at high incident particle rates. The early MPGD developments culminated in the formation of the RD51 collaboration which has become the critical organization for the promotion of MPGDs and all aspects of their production, characterization, simulation, and uses in an expanding array of experimental configurations. For the Snowmass 2021 study, a number of Letters of Interest were received that illustrate ongoing developments and expansion of the use of MPGDs. In this paper, we highlight high precision timing, high rate application, trigger capability expansion of the SRS readout system, and a structure designed for low ion backflow.

physics.ins-det↗

arXiv2022

Rate-capability of the VMM3a Front End in the RD51 Scalable Readout System

The VMM3a is an Application Specific Integrated Circuit (ASIC), specifically developed for the readout of gaseous detectors. Originally developed within the ATLAS New Small Wheel (NSW) upgrade, it has been successfully integrated into the Scalable Readout System (SRS) of the RD51 collaboration. This allows, to use the VMM3a also in small laboratory set-ups and mid-scale experiments, which make use of Micro-Pattern Gaseous Detectors (MPGDs). As part of the integration of the VMM3a into the SRS, the readout and data transfer scheme was optimised to reach a high rate-capability of the entire readout system and profit from the VMM3a's high single-channel rate-capability of 3.6 Mhits/s. The optimisation focused mainly on the handling of the data output stream of the VMM3a, but also on the development of a trigger-logic between the front-end cards and the DAQ computer. In this article, two firmware implementations of the non-ATLAS continuous readout mode are presented, as well as the implementation of the trigger-logic. Afterwards, a short overview on X-ray imaging results is presented, to illustrate the high rate-capability rom an application point-of-view.

physics.ins-det↗

arXiv2021

Characterisation of the dip-bump structure observed in proton-proton elastic scattering at $\sqrt s$ = 8 TeV

The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton-proton scattering at $\sqrt{s} = 8\ {\rm TeV}$ in the squared four-momentum transfer range $0.2\ {\rm GeV^{2}} < |t| < 1.9\ {\rm GeV^{2}}$. This interval includes the structure with a diffractive minimum ("dip") and a secondary maximum ("bump") that has also been observed at all other LHC energies, where measurements were made. A detailed characterisation of this structure for $\sqrt{s} = 8\ {\rm TeV}$ yields the positions, $|t|_{\rm dip} = (0.521 \pm 0.007)\ {\rm GeV^2}$ and $|t|_{\rm bump} = (0.695 \pm 0.026)\ {\rm GeV^2}$, as well as the cross-section values, ${{\rm d}σ/{\rm d} t}_{\rm dip} = (15.1 \pm 2.5)\ {\rm{μb/GeV^2}}$ and ${{\rm d}σ/{\rm d} t}_{\rm bump} = (29.7 \pm 1.8)\ {\rm{μb/GeV^2}}$, for the dip and the bump, respectively.

hep-ex↗

arXiv2021

Timing performance of a multi-pad PICOSEC-Micromegas detector prototype

The multi-pad PICOSEC-Micromegas is an improved detector prototype with a segmented anode, consisting of 19 hexagonal pads. Detailed studies are performed with data collected in a muon beam over four representative pads. We demonstrate that such a device, scalable to a larger area, provides excellent time resolution and detection efficiency. As expected from earlier single-cell device studies, we measure a time resolution of approximately 25 picoseconds for charged particles hitting near the anode pad centers, and up to 30 picoseconds at the pad edges. Here, we study in detail the effect of drift gap thickness non-uniformity on the timing performance and evaluate impact position based corrections to obtain a uniform timing response over the full detector coverage.

physics.ins-det↗

arXiv2020

Modeling the Timing Characteristics of the PICOSEC Micromegas Detector

The PICOSEC Micromegas detector can time the arrival of Minimum Ionizing Particles with a sub-25 ps precision. A very good timing resolution in detecting single photons is also demonstrated in laser beams. The PICOSEC timing resolution is determined mainly by the drift field. The arrival time of the signal and the timing resolution vary with the size of the pulse amplitude. Detailed simulations based on GARFIELD++ reproduce the experimental PICOSEC timing characteristics. This agreement is exploited to identify the microscopic physical variables, which determine the observed timing properties. In these studies, several counter-intuitive observations are made for the behavior of such microscopic variables. In order to gain insight on the main physical mechanisms causing the observed behavior, a phenomenological model is constructed and presented. The model is based on a simple mechanism of "time-gain per interaction" and it employs a statistical description of the avalanche evolution. It describes quantitatively the dynamical and statistical properties of the microscopic quantities, which determine the PICOSEC timing characteristics, in excellent agreement with the simulations. In parallel, it offers phenomenological explanations for the behavior of these microscopic variables. The formulae expressing this model can be used as a tool for fast and reliable predictions, provided that the input parameter values (e.g. drift velocities) are known for the considered operating conditions.

physics.ins-det↗

arXiv2020

Optical Readout Studies of the Thick-COBRA Gaseous Detector

The performance of a Thick-COBRA (THCOBRA) gaseous detector is studied using an optical readout technique. The operation principle of this device is described, highlighting its operation in a gas mixture of Ar/CF4 (80/20%) for visible scintillation light emission. The contributions to the total gain from the holes and the anode strips as a function of the applied bias voltage were visualized. The preservation of spatial information from the initial ionizations was demonstrated by analyzing the light emission from 5.9keV X-rays of an 55Fe source. The observed non-uniformity of the scintillation light from the holes supports the claim of a space localization accuracy better than the pitch of the holes. The acquired images were used to identify weak points and sources of instabilities in view of the development of new optimized structures.

physics.ins-det↗

arXiv2019

New Technologies for Discovery

For the field of high energy physics to continue to have a bright future, priority within the field must be given to investments in the development of both evolutionary and transformational detector development that is coordinated across the national laboratories and with the university community, international partners and other disciplines. While the fundamental science questions addressed by high energy physics have never been more compelling, there is acute awareness of the challenging budgetary and technical constraints when scaling current technologies. Furthermore, many technologies are reaching their sensitivity limit and new approaches need to be developed to overcome the currently irreducible technological challenges. This situation is unfolding against a backdrop of declining funding for instrumentation, both at the national laboratories and in particular at the universities. This trend has to be reversed for the country to continue to play a leadership role in particle physics, especially in this most promising era of imminent new discoveries that could finally break the hugely successful, but limited, Standard Model of fundamental particle interactions. In this challenging environment it is essential that the community invest anew in instrumentation and optimize the use of the available resources to develop new innovative, cost-effective instrumentation, as this is our best hope to successfully accomplish the mission of high energy physics. This report summarizes the current status of instrumentation for high energy physics, the challenges and needs of future experiments and indicates high priority research areas.

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