arXiv subjects

L. Sestini

Publications and source records attributed to L. Sestini.

7 recordsLinked to original sources

arXiv2026

Design and beam-test characterization of the CRILIN semi-homogeneous crystal calorimeter

CRILIN is a high-granularity semi-homogeneous electromagnetic calorimeter based on longitudinally segmented PbF$_2$ crystal matrices read out by UV-extended silicon photomultipliers. The concept combines fast Cherenkov response, fine transverse granularity, longitudinal shower information, and radiation tolerance for future lepton-collider experiments. This paper reports the construction of a large-area prototype and its performance measured in beam tests at the CERN SPS. The detector comprises five $7\times7$ PbF$_2$ crystal matrices, has a depth of about $22X_0$, and is read out by four $3\times3~\mathrm{mm}^2$ SiPMs per crystal integrated in a single electronic channel. Electron data between 10 and 120~GeV and dedicated 150~GeV muon data were used to characterize the detector response. A time resolution below 50~ps is achieved for electron energies above 10~GeV, reaching values below 20~ps above 60~GeV. The energy resolution is described by a stochastic term of $(6.58\pm0.04)\%/\sqrt{E/\mathrm{GeV}}$ and a constant term of $(0.23\pm0.02)\%$, with an additional noise contribution fixed from pedestal data. The longitudinal segmentation enables event-by-event corrections based on the reconstructed shower development, resulting in a significant improvement of the energy resolution. A light yield of approximately 0.54~photoelectrons/MeV is measured consistently using both electron showers and minimum-ionizing particles. A Geant4-based simulation incorporating the relevant experimental effects reproduces the measured energy resolution. These results validate the CRILIN architecture as a compact, fast, and longitudinally segmented electromagnetic calorimeter for future collider experiments.

physics.ins-det↗

arXiv2026

3D software compensation of hadronic showers in the CRILIN crystal calorimeter

Future electron-positron Higgs factories require excellent jet energy resolution to perform precision measurements of Higgs boson couplings to quarks and gluons. Although homogeneous crystal calorimeters provide remarkable electromagnetic energy resolution, their highly non-compensating response makes hadronic energy reconstruction particularly challenging. In this work, software compensation techniques are investigated for CRILIN, a longitudinally segmented Cherenkov crystal electromagnetic calorimeter based on PbF$_2$ crystals. Using Geant4 simulations of pion showers, it is shown that shower-shape observables are strongly correlated with the fraction of deposited energy reconstructed in a CRILIN module. Simple event-by-event corrections based on the shower transverse RMS and longitudinal center-of-gravity already yield a substantial improvement in hadronic energy reconstruction. A ParticleNet Graph Neural Network exploiting the full three-dimensional shower topology achieves significantly improved performance with respect to simple energy sum reconstruction. Under several different assumptions for the downstream hadronic calorimeter resolution, the GNN-based reconstruction significantly reduces the effective CRILIN contribution to the combined calorimetric resolution, therefore preserving an excellent combined ECAL+HCAL performance. The dependence of the result on the assumed HCAL resolution is also studied and found to be limited within the range considered. These results demonstrate that highly granular crystal calorimeters can recover a large fraction of the information lost because of their intrinsically non-compensating response through software-based compensation techniques, enabling excellent hadronic energy resolution in a combined ECAL+HCAL system and making such detectors promising candidates for future collider experiments.

hep-ex↗

arXiv2022

Crilin: A CRystal calorImeter with Longitudinal InformatioN for a future Muon Collider

The measurement of physics processes at new energy frontier experiments requires excellent spatial, time, and energy resolutions to resolve the structure of collimated high-energy jets. In a future Muon Collider, the beam-induced backgrounds (BIB) represent the main challenge in the design of the detectors and of the event reconstruction algorithms. The technology and the design of the calorimeters should be chosen to reduce the effect of the BIB, while keeping good physics performance. Several requirements can be inferred: i) high granularity to reduce the overlap of BIB particles in the same calorimeter cell; ii) excellent timing (of the order of 100 ps) to reduce the out-of-time component of the BIB; iii) longitudinal segmentation to distinguish the signal showers from the fake showers produced by the BIB; iv) good energy resolution (less than 10%/sqrt(E)) to obtain good physics performance, as has been already demonstrated for conceptual particle flow calorimeters. Our proposal consists of a semi-homogeneous electromagnetic calorimeter based on Lead Fluoride Crystals (PbF2) readout by surface-mount UV-extended Silicon Photomultipliers (SiPMs): the Crilin calorimeter. In this paper, the performances of the Crilin calorimeter in the Muon Collider framework for hadron jets reconstruction have been analyzed. We report the single components characterizations together with the development of a small-scale prototype, consisting of 2 layers of 3x3 crystals each.

physics.ins-det↗

arXiv2022

A Muon Collider Facility for Physics Discovery

Muon colliders provide a unique route to deliver high energy collisions that enable discovery searches and precision measurements to extend our understanding of the fundamental laws of physics. The muon collider design aims to deliver physics reach at the highest energies with costs, power consumption and on a time scale that may prove favorable relative to other proposed facilities. In this context, a new international collaboration has formed to further extend the design concepts and performance studies of such a machine. This effort is focused on delivering the elements of a $\sim$10 TeV center of mass (CM) energy design to explore the physics energy frontier. The path to such a machine may pass through lower energy options. Currently a 3 TeV CM stage is considered. Other energy stages could also be explored, e.g. an s-channel Higgs Factory operating at 125 GeV CM. We describe the status of the R&D and design effort towards such a machine and lay out a plan to bring these concepts to maturity as a tool for the high energy physics community.

physics.acc-ph↗

arXiv2021

Muon detection in electron-positron annihilation for muon collider studies

The investigation of the energy frontier in physics requires novel concepts for future colliders. The idea of a muon collider is very appealing since it would allow to study particle collisions at up to tens of TeV energy, while offering a cleaner experimental environment with respect to hadronic colliders. One key element in the muon collider design is the low-emittance muon production. Recently,the Low EMittance Muon Accelerator (LEMMA) collaboration has explored the muon pair production close to its kinematic threshold by annihilating 45 GeV positrons with electrons in a low Z material target. In this configuration, muons are emerging from the target with a naturally low-emittance. In this paper we describe the performance of a system, to study this production mechanism, that consists in several segmented absorbers with alternating active layers composed of fast Cherenkov detectors together with a muon identification technique based on this detector. Passive layers were made of tungsten. We collected data corresponding to muon and electron beams produced at the H2 line in the North Area of the European Organization for Nuclear Research (CERN) in September 2018.

physics.ins-det↗

arXiv2020

Study of muon pair production from positron annihilation at threshold energy

The muon collider represents one of the most promising solutions for a future machine exploring the high energy frontier, but several challenges due to the 2.2 $μ$sec muon lifetime at rest have to be carefully considered. The LEMMA project is investigating the possibility of producing low emittance muon/antimuon pairs from the e$^+$e$^-$ annihilation process at threshold energy, resulting in small transverse emittance beams without any additional beam cooling. However most of the measurements available are performed at higher $\sqrt{s}$ values. It is therefore necessary to measure muons production in positron annihilation at threshold energy and compare the experimental results with the predictions in this specific energy regime. Apart from being a topic of physical interest by itself, these near to threshold measurements can have a sizeable impact on the estimation of the ultimate luminosity achievable in a muon collider with the LEMMA injection scheme.

hep-ex↗

arXiv2019

Positron driven muon source for a muon collider

The design of a future multi-TeV muon collider needs new ideas to overcome the technological challenges related to muon production, cooling, accumulation and acceleration. In this paper a layout of a positron driven muon source known as the Low EMittance Muon Accelerator (LEMMA) concept is presented. The positron beam, stored in a ring with high energy acceptance and low emittance, is extracted and driven to a multi-target system, to produce muon pairs at threshold. This solution alleviates the issues related to the power deposited and the integrated Peak Energy Density Deposition (PEDD) on the targets. Muons produced in the multi-target system will then be accumulated before acceleration and injection in the collider. A multi-target line lattice has been designed to cope with the focusing of both the positron and muon beams. Studies on the number, material and thickness of the targets have been carried out. A general layout of the overall scheme and a description is presented, as well as plans for future R&D.

physics.acc-ph↗