A
bstract
The Compact Linear Collider (CLIC) is a proposed future high-luminosity linear electron-positron collider operating at three energy stages, with nominal centre-of-mass energies
s
= 380 GeV, ...1
.
5 TeV, and 3 TeV. Its aim is to explore the energy frontier, providing sensitivity to physics beyond the Standard Model (BSM) and precision measurements of Standard Model processes with an emphasis on Higgs boson and top-quark physics. The opportunities for top-quark physics at CLIC are discussed in this paper. The initial stage of operation focuses on top-quark pair production measurements, as well as the search for rare flavour-changing neutral current (FCNC) top-quark decays. It also includes a top-quark pair production threshold scan around 350 GeV which provides a precise measurement of the top-quark mass in a well-defined theoretical framework. At the higher-energy stages, studies are made of top-quark pairs produced in association with other particles. A study of t
̄
tH production including the extraction of the top Yukawa coupling is presented as well as a study of vector boson fusion (VBF) production, which gives direct access to high-energy electroweak interactions. Operation above 1 TeV leads to more highly collimated jet environments where dedicated methods are used to analyse the jet constituents. These techniques enable studies of the top-quark pair production, and hence the sensitivity to BSM physics, to be extended to higher energies. This paper also includes phenomenological interpretations that may be performed using the results from the extensive top-quark physics programme at CLIC.
Development of Micromegas detectors with resistive anode pads Chefdeville, M.; de Oliveira, R.; Drancourt, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2021, Volume:
1003
Journal Article
Peer reviewed
Open access
A novel type of resistive Micromegas combining a Bulk mesh and a resistive pad board is presented. Readout pads are covered by a thin insulating layer with a top resistive coating segmented into ...resistive pads. Readout and resistive pads are electrically connected by means of planar resistors embedded in the insulator, enabling fast clearance of the avalanche charge from the resistive surface. The maximum gas gain achieved by these resistive detectors is similar to that of non-resistive Micromegas. A possible saturation of the gain for large energy deposits in the gas was investigated by means of 55Fe quanta and electromagnetic showers in the 30–200GeV energy range, but no significant deviation from a proportional response was found. With a suitable choice of the resistance, these detectors demonstrate negligible gain drop and no sparking up to X-ray fluxes of ∼1MHz/mm2 which constitutes a major improvement over non-resistive Micromegas. Spark suppression was also verified in a hadron beam for prototypes with a pad resistance as low as 40kΩ or above. Passive protections of the front-end electronics against sparks (diodes on a printed circuit board) are therefore not required for these resistive detectors.
Originally introduced to improve the rate capability of traditional wire chambers, Micro Pattern Gaseous Detectors (MPGD) actually demonstrate many more benefits. Be it for medical and industry ...imaging, collider experiments or more interestingly in the framework of this conference for the search of rare events, they are the subject of constant research and development in several laboratories over the world. The RD51 collaboration has been coordinating this work since April 2008 and is meant to advance the technological development and application of MPGD. The collaboration is presented and emphasis is put on its latest achievements which do make these devices an attractive option for the detection of low energy rare events: the possibility to instrument large area and to detect UV photons.
We present a study of the response of the highly granular Digital Hadronic Calorimeter with steel absorbers, the Fe-DHCAL, to positrons, muons, and pions with momenta ranging from 2 to 60GeV/c. ...Developed in the context of the CALICE collaboration, this hadron calorimeter utilises Resistive Plate Chambers as active media, interspersed with steel absorber plates. With a transverse granularity of 1×1cm2 and a longitudinal segmentation of 38 layers, the calorimeter counted 350,208 readout channels, each read out with single-bit resolution (digital readout). The data were recorded in the Fermilab test beam in 2010–11. The analysis includes measurements of the calorimeter response and the energy resolution to positrons and muons, as well as detailed studies of various shower shape quantities. The results are compared to simulations based on Geant4, which utilise different electromagnetic and hadronic physics lists.
Towards MPGD-based (S)DHCAL Shaked Renous, D.; Bhattacharya, P.; Chefdeville, M. ...
Journal of physics. Conference series,
04/2020, Volume:
1498, Issue:
1
Journal Article
Peer reviewed
Open access
Digital and Semi-Digital Hadronic Calorimeters ((S)DHCAL) were suggested for future Colliders as part of the particle-flow concept. Though studied mostly with Resistive Plate Chambers (RPC), studies ...focusing on Micro-Pattern Gaseous Detector (MPGD)-based sampling elements have shown the potential advantages using such techniques. In 2018, eight 48x48 cm2 sampling elements based on resistive Micromegas and Resistive Plate WELL (RPWELL) technologies were assembled. They were tested within a small MPGD-based SDHCAL prototype incorporating in addition three 16x16 cm2 Micromegas detectors and steel absorber plates recording hadronic showers of low-energy pions at the CERN/PS beam line. Preliminary results and analysis methodology are presented, using data samples recorded with pions with momenta in the range from 2 to 6 GeV/c.
The use of pixel readout chips as highly segmented anodes of gaseous detectors offers high granularity and low noise at the input of each channel. This readout can be applied to TPCs for high energy ...particle tracking as well as for low energy recoil detection where a small charge is created in the gas volume. Detectors combining GEM or Micromegas amplification stages with pixel readout chips will be presented and their tracking capabilities described.
Resistive micromegas is proposed as an active element for sampling calorimetry. Future linear collider experiments or the HL-LHC experiments can profit from those developments for Particle Flow ...Calorimetry. Micromegas possesses remarkable properties concerning gain stability, reduced ion feedback, response linearity, adaptable sensitive element granularity, fast response and high rate capability. Recent developments on Micromegas with a protective resistive layer present excellent results, resolving the problem of discharges caused by local high charge deposition, thanks to its RC-slowed charge evacuation. Higher resistivity though, may cause loss of the response linearity at high rates. We have scanned a wide range of resistivities and performed laboratory tests with X-rays that demonstrate excellent response linearity up to rates of (a few) times 10
MHz
/
cm
2
, with simultaneous mitigation of discharges. Beam test studies at SPS/CERN with hadrons have also shown a remarkable stability of the resistive Micromegas and low currents for rates up to 15
MHz
/
cm
2
. We present results from the aforementioned studies confronted with MC simulation
The application of Micromegas for sampling calorimetry puts specific constraints on the design and performance of this gaseous detector. In particular, uniform and linear response, low noise and ...stability against high ionisation density deposits are prerequisites for achieving good energy resolution. A Micromegas-based hadronic calorimeter was proposed for an application at a future linear collider experiment and three technologically advanced prototypes of 1×1m2 were constructed. Their merits relative to the above-mentioned criteria are discussed on the basis of measurements performed at the CERN SPS test-beam facility.
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