arXiv subjects

M. Zito

Publications and source records attributed to M. Zito.

10 recordsLinked to original sources

arXiv2025

Performance of the High-Angle Time Projection Chambers in the Upgraded T2K Off-Axis Near Detector

The off-axis magnetic near detector of the T2K experiment has undergone a significant upgrade, including the construction and installation of two new Time Projection Chambers featuring innovative resistive Micromegas technology and a field cage composed of thin composite walls. This paper provides a detailed description of the new components of the chambers, including the gas system, gas monitoring chambers, and data acquisition system. Additionally, it reports the results of extensive testing using both neutrino beams and cosmic rays, with comparisons between data and Monte Carlo simulations. The new detectors achieve improved spatial resolution and enhanced particle identification capabilities which are crucial for the precision goals of the T2K experiment.

physics.ins-det↗

arXiv2025

Characterization of the Electronic Noise in the Readout of Resistive Micromegas in the High-Angle Time Projection Chambers of the T2K Experiment

The two high-angle Time Projection Chambers of the T2K experiment are equipped with a new readout system based on resistive Micromegas detector technology, and utilize custom-made electronics based on AFTER chips for signal processing. This study analyzes and characterizes the electronic noise of the detector readout chain to develop a comprehensive noise model. The model enables the generation of Monte Carlo simulations to investigate systematic effects in signal processing. The analysis is based on data collected from 32 resistive Micromegas detectors, recorded without zero suppression. All detectors exhibit a quasi-identical and time-stable noise level. The developed analytical model accurately describes the observed noise, and derived Monte Carlo simulations show excellent agreement with experimental data.

physics.ins-det↗

arXiv2023

Characterization of Charge Spreading and Gain of Encapsulated Resistive Micromegas Detectors for the Upgrade of the T2K Near Detector Time Projection Chambers

An upgrade of the near detector of the T2K long baseline neutrino oscillation experiment is currently being conducted. This upgrade will include two new Time Projection Chambers, each equipped with 16 charge readout resistive Micromegas modules. A procedure to validate the performance of the detectors at different stages of production has been developed and implemented to ensure a proper and reliable operation of the detectors once installed. A dedicated X-ray test bench is used to characterize the detectors by scanning each pad individually and to precisely measure the uniformity of the gain and the deposited energy resolution over the pad plane. An energy resolution of about 10% is obtained. A detailed physical model has been developed to describe the charge dispersion phenomena in the resistive Micromegas anode. The detailed physical description includes initial ionization, electron drift, diffusion effects and the readout electronics effects. The model provides an excellent characterization of the charge spreading of the experimental measurements and allowed the simultaneous extraction of gain and RC information of the modules.

physics.ins-det↗

arXiv2022

Analysis of test beam data taken with a prototype of TPC with resistive Micromegas for the T2K Near Detector upgrade

In this paper we describe the performance of a prototype of the High Angle Time Projection Chambers (HA-TPCs) that are being produced for the Near Detector (ND280) upgrade of the T2K experiment. The two HA-TPCs of ND280 will be instrumented with eight Encapsulated Resistive Anode Micromegas (ERAM) on each endplate, thus constituting in total 32 ERAMs. This innovative technique allows the detection of the charge emitted by ionization electrons over several pads, improving the determination of the track position. The TPC prototype has been equipped with the first ERAM module produced for T2K and with the HA-TPC readout electronics chain and it has been exposed to the DESY Test Beam in order to measure spatial and dE/dx resolution. In this paper we characterize the performances of the ERAM and, for the first time, we compare them with a newly developed simulation of the detector response. Spatial resolution better than 800 ${\mu \rm m}$ and dE/dx resolution better than 10% are observed for all the incident angles and for all the drift distances of interest. All the main features of the data are correctly reproduced by the simulation and these performances fully fulfill the requirements for the HA-TPCs of T2K.

physics.ins-det↗

arXiv2021

Characterization of resistive Micromegas detectors for the upgrade of the T2K Near Detector Time Projection Chambers

The second phase of the T2K experiment is expected to start data taking in autumn 2022. An upgrade of the Near Detector (ND280) is under development and includes the construction of two new Time Projection Chambers called High-Angle TPC (HA-TPC). The two endplates of these TPCs will be paved with eight Micromegas type charge readout modules. The Micromegas detector charge amplification structure uses a resistive anode to spread the charges over several pads to improve the space point resolution. This innovative technique is combined with the bulk-Micromegas technology to compose the "Encapsulated Resistive Anode Micromegas" detector. A prototype has been designed, built and exposed to an electron beam at the DESY II test beam facility. The data have been used to characterize the charge spreading and to produce a RC map. Spatial resolution better than 600 $\mu$m and energy resolution better than 9% are obtained for all incident angles. These performances fulfil the requirements for the upgrade of the ND280 TPC.

physics.ins-det↗

arXiv2019

Performances of a resistive MicroMegas module for the Time Projection Chambers of the T2K Near Detector upgrade

An upgrade of the Near Detector of the T2K long baseline neutrino oscillation experiment, ND280, has been proposed. This upgrade will include two new Time Projection Chambers, each equipped with 16 resistive MicroMegas modules for gas amplification. A first prototype of resistive MicroMegas has been designed, built, installed in the HARP field cage, and exposed to a beam of charged particles at CERN. The data have been used to characterize the performances of the resistive MicroMegas module. A spatial resolution of 300 $μm$ and a deposited energy resolution of 9% were observed for horizontal electrons crossing the TPCs at 30 cm from the anode. Such performances fully satisfy the requirements for the upgrade of the ND280 TPC.

physics.ins-det↗

arXiv2013

The EUROnu Project

The EUROnu project has studied three possible options for future, high intensity neutrino oscillation facilities in Europe. The first is a Super Beam, in which the neutrinos come from the decay of pions created by bombarding targets with a 4 MW proton beam from the CERN High Power Superconducting Proton Linac. The far detector for this facility is the 500 kt MEMPHYS water Cherenkov, located in the Fréjus tunnel. The second facility is the Neutrino Factory, in which the neutrinos come from the decay of μ+ and μ- beams in a storage ring. The far detector in this case is a 100 kt Magnetised Iron Neutrino Detector at a baseline of 2000 km. The third option is a Beta Beam, in which the neutrinos come from the decay of beta emitting isotopes, in particular 6He and 18Ne, also stored in a ring. The far detector is also the MEMPHYS detector in the Fréjus tunnel. EUROnu has undertaken conceptual designs of these facilities and studied the performance of the detectors. Based on this, it has determined the physics reach of each facility, in particular for the measurement of CP violation in the lepton sector, and estimated the cost of construction. These have demonstrated that the best facility to build is the Neutrino Factory. However, if a powerful proton driver is constructed for another purpose or if the MEMPHYS detector is built for astroparticle physics, the Super Beam also becomes very attractive.

physics.acc-ph↗

arXiv2012

The SPL-based Neutrino Super Beam

The EUROnu Super Beam work package has studied a neutrino beam based on SPL at CERN and aimed at MEMPHYS, a large water Cherenkov detector, proposed for the Laboratoire Souterrain de Modane (Fréjus tunnel, France), with a baseline of 130 km. The aim of this proposed experiment is to study the CP violation in the neutrino sector. In the study reported here, we have developed the conceptual design of the neutrino beam, especially the target and the magnetic focusing device. Indeed, this beam present several unprecedented challenges, like the high primary proton beam power (4 MW), the high repetition rate (50 Hz) and the low energy of the protons (4.5 GeV). The design is completed by a study of all the main component of the system, starting from the transport system to guide the beam to the target up to the beam dump.

physics.acc-ph↗

arXiv1999

Inclusive decay of B mesons into $D_s$ or $D^*_s$

We compute the inclusive decay rates $b \to D_s^-(D^{*-}_s) c$ including lowest order QCD corrections on the quark legs, and compare with existing data. Unlike the short distance QCD corrections, that are of higher order, these corrections are of order $α_s$. In the on-shell renormalization scheme and for $α_s(m_b) \cong 0.2$ we find a correction of -10% to the inclusive rate computed using factorization. This gives a total rate $BR(b \to D_s^-(D^{*-}_s)c) \cong 8%$ consistent within $1σ$ with the measured value $BR(B \to D_s^{\pm}X) = (10.0 \pm 2.5)%$. The general formulae given here include the case of vanishing mass for the final quark $b \to D_s^-(D_s^{*-})u$. The radiative correction to this rate is -17%. We show in another place that this process can be useful for the measurement of the CKM matrix element $V_{ub}$. We also give the renormalized vertex at the interesting values $q^2 = 0$ and $q^2 = q_{max}^2$, and compare with existing literature.

hep-ph↗

arXiv1999

Measuring $|V_{ub}|$ with B$\to D_s^+ X_u$ transitions

We propose the determination of the CKM matrix element $|V_{ub}|$ by the measurement of the spectrum of $B \to D_s^+ X_u$, dominated by the spectator quark model mechanism $\bar{b} \to D_s^{(*)+} \bar{u}$. The interest of considering $B \to D_s^+X_u$ versus the semileptonic decay is that more than 50 % of the spectrum for $B \to D_s^+ X_u$ occurs above the kinematical limit for $B \to D_s^+ X_c$, while most of the spectrum $B \to l νX_u$ occurs below the $B \to l νX_c$ one. Furthermore, the measure of the hadronic mass $M_X$ is easier in the presence of an identified $D_s$ than when a $ν$ has been produced. As a consistency check, we point out that the rate $\bar{b} \to D_s^{(*)+} \bar{c}$ (including QCD corrections that we present elsewhere) is consistent with the measured $BR (B \to D_s^{\pm} X)$. Although the hadronic complications may be more severe in the mode that we propose than in the semileptonic inclusive decay, the end of the spectrum in $B \to l νX_u$ is not well understood on theoretical grounds. We argue that, in our case, the excited $D_s^{**}$, decaying into $D K$, do not contribute and, if there is tagging of the $B$ meson, the other mechanisms to produce a $D_s$ of the right sign are presumably small, of $O(10^{-2})$ relative to the spectator amplitude, or can be controlled by kinematical cuts. In the absence of tagging, other hadronic backgrounds deserve careful study. We present a feasability study with the BaBar detector.

hep-ph↗