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, Letnik:
1003
Journal Article
Recenzirano
Odprti dostop
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.
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
We explore the possibility of interpreting the solar and atmospheric neutrino data within the context of the Minimal Supersymmetric Standard Model augmented by a single U(1) anomalous family symmetry ...spontaneously broken by non-zero vacuum expectation values of a pair of singlet fields. The symmetry retains a dimension-five operator which provides Majorana masses for left-handed neutrino states. Assuming symmetric lepton mass matrices, the model predicts inverse hierarchical neutrino mass spectrum, θ13=0 and large mixing while at the same time it provides acceptable mass matrices for the charged fermions.
In July 2012, the ATLAS and CMS collaborations at the CERN Large Hadron Collider announced the observation of a Higgs boson at a mass of around 125 gigaelectronvolts. Ten years later, and with the ...data corresponding to the production of a 30-times larger number of Higgs bosons, we have learnt much more about the properties of the Higgs boson. The CMS experiment has observed the Higgs boson in numerous fermionic and bosonic decay channels, established its spin-parity quantum numbers, determined its mass and measured its production cross-sections in various modes. Here the CMS Collaboration reports the most up-to-date combination of results on the properties of the Higgs boson, including the most stringent limit on the cross-section for the production of a pair of Higgs bosons, on the basis of data from proton-proton collisions at a centre-of-mass energy of 13 teraelectronvolts. Within the uncertainties, all these observations are compatible with the predictions of the standard model of elementary particle physics. Much evidence points to the fact that the standard model is a low-energy approximation of a more comprehensive theory. Several of the standard model issues originate in the sector of Higgs boson physics. An order of magnitude larger number of Higgs bosons, expected to be examined over the next 15 years, will help deepen our understanding of this crucial sector.
A long optical base line spectrophotometer designed to measure light transmission in deep sea waters is described. The variable optical path length allows measurements without the need for absolute ...or external calibration. The spectrophotometer uses eight groups of uncollimated light sources emitting in the range 370–530
nm and was deployed at various depths at two locations in the Ionian Sea that are candidate sites for a future underwater neutrino telescope. Light transmission spectra at the two locations are presented and compared.
Light transmission measurements with LAMS in the Mediterranean Sea Anassontzis, E.G.; Ball, A.E.; Belias, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2011, Letnik:
626
Journal Article
Recenzirano
The long optical base transmissometer (LAMS—Long Arm Marine Spectrophotometer) constructed in 2008 by NESTOR group is described. The data of the recent water transparency measurements in the NESTOR ...site and in the Capo Passero site in the wavelength range 378–522
nm are presented
In this paper, we study scalar mediator induced nonstandard interactions (SNSIs) in the context of the ESSnuSB experiment. In particular, we study the capability of ESSnuSB to put bounds on the SNSI ...parameters and also study the impact of SNSIs in the measurement of the leptonic C P phase δ C P . Existence of SNSIs modifies the neutrino mass matrix and this modification can be expressed in terms of three diagonal real parameters ( η e e , η μ μ , and η τ τ ) and three off-diagonal complex parameters ( η e μ , η e τ , and η μ τ ). Our study shows that the upper bounds on the parameters η μ μ and η τ τ depend upon how Δ m 31 2 is minimized in the theory. However, this is not the case when one tries to measure the impact of SNSIs on δ C P . Further, we show that the C P sensitivity of ESSnuSB can be completely lost for certain values of η e e and η μ τ for which the appearance channel probability becomes independent of δ C P . Published by the American Physical Society 2024
Abstract A search for new long-lived particles decaying to leptons using proton–proton collision data produced by the CERN LHC at $$\sqrt{s}=13\,\text {Te}\text {V} $$ s = 13 Te is presented. Events ...are selected with two leptons (an electron and a muon, two electrons, or two muons) that both have transverse impact parameter values between 0.01 and 10 $$\,\text {cm}$$ cm and are not required to form a common vertex. Data used for the analysis were collected with the CMS detector in 2016, 2017, and 2018, and correspond to an integrated luminosity of 118 (113) $$\,\text {fb}^{-1}$$ fb - 1 in the $${{\mathrm{e}}_{\mathrm{}}^{\mathrm{}}} {{\mathrm{e}}_{\mathrm{}}^{\mathrm{}}} $$ e e channel ( $${{\mathrm{e}}_{\mathrm{}}^{\mathrm{}}} {\upmu } $$ e μ and $${\upmu } {\upmu } $$ μ μ channels). The search is designed to be sensitive to a wide range of models with displaced $${{\mathrm{e}}_{\mathrm{}}^{\mathrm{}}} {\upmu } $$ e μ , $${{\mathrm{e}}_{\mathrm{}}^{\mathrm{}}} {{\mathrm{e}}_{\mathrm{}}^{\mathrm{}}} $$ e e , and $${\upmu } {\upmu } $$ μ μ final states. The results constrain several well-motivated models involving new long-lived particles that decay to displaced leptons. For some areas of the available phase space, these are the most stringent constraints to date.
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