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A. Aloisio

Publications and source records attributed to A. Aloisio.

152 records · Page 9Linked to original sources
arXiv2018

First Measurements of Beam Backgrounds at SuperKEKB

The high design luminosity of the SuperKEKB electron-positron collider is expected to result in challenging levels of beam-induced backgrounds in the interaction region. Properly simulating and mitigating these backgrounds is critical to the success of the Belle~II experiment. We report on measurements performed with a suite of dedicated beam background detectors, collectively known as BEAST II, during the so-called Phase 1 commissioning run of SuperKEKB in 2016, which involved operation of both the high energy ring (HER) of 7 GeV electrons as well as the low energy ring (LER) of 4 GeV positrons. We describe the BEAST II detector systems, the simulation of beam backgrounds, and the measurements performed. The measurements include standard ones of dose rates versus accelerator conditions, and more novel investigations, such as bunch-by-bunch measurements of injection backgrounds and measurements sensitive to the energy spectrum and angular distribution of fast neutrons. We observe beam-gas, Touschek, beam-dust, and injection backgrounds. We do not observe significant synchrotron radiation, as expected. Measured LER beam-gas backgrounds and Touschek backgrounds in both rings are slightly elevated, on average three times larger than the levels predicted by simulation. HER beam-gas backgrounds are on on average two orders of magnitude larger than predicted. Systematic uncertainties and channel-to-channel variations are large, so that these excesses constitute only 1-2 sigma level effects. Neutron background rates are higher than predicted and should be studied further. We will measure the remaining beam background processes, due to colliding beams, in the imminent commissioning Phase 2. These backgrounds are expected to be the most critical for Belle II, to the point of necessitating replacement of detector components during the Phase 3 (full-luminosity) operation of SuperKEB.

physics.ins-det↗
arXiv2009

Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN.

hep-ex↗
arXiv2005

Measurement of $σ(e^+e^-\to π^+ π^- γ)$ and extraction of $σ(e^+e^-\to π^+π^-)$ below 1 {\rm GeV} with the KLOE detector

We have measured the cross section $σ(e^+e^-\to π^+π^- γ)$ at an energy $W=m_ϕ=1.02$ GeV with the KLOE detector at the electron-positron collider DA$Φ$NE. From the dependence of the cross section on the invariant mass of the two-pion system, we extract $σ(e^+e^-\to π^+π^-)$ for the mass range $0.35<s<0.95$ GeV$^2$. From this result, we calculate the pion form factor and the hadronic contribution to the muon anomaly, $a_μ$.

hep-ex↗
arXiv2004

Upper Limit on the eta to gamma gamma gamma Branching Ratio with the KLOE Detector

We have searched for the C-violating decay eta to gamma gamma gamma in a sample of ~ 18 million eta mesons produced in phi to eta gamma decays, collected with the KLOE detector at the Frascati phi-factory DAFNE. No signal is observed and we obtain the upper limit BR(eta to gamma gamma gamma) less equal than 1.6x10^(-5) at 90 % C.L.

hep-ex↗
arXiv2003

Determination of $σ(e^+e^-\to π^+ π^-)$ from radiative processes at DA$Φ$NE

We have measured the cross section $σ(e^+e^-\toπ^+π^-γ)$ with the KLOE detector at DA$Φ$NE, at an energy $W=M_ϕ=1.02$ GeV. From the dependence of the cross section on $m(π^+π^-)=\sqrt{W^2-2WE_γ}$, where $E_γ$ is the energy of the photon radiated from the initial state, we extract $σ(e^+e^-\toπ^+π^-)$ for the mass range $0.35<m^2(π^+π^-)<0.95$ GeV$^2$. From our result we extract the pion form factor and the hadronic contribution to the muon anomaly, $a_μ$.

hep-ex↗
arXiv2003

Searching for eta to 3 gamma decay

Data collected by the KLOE experiment in years 2001/2002 for a total integrated luminosity of 410 pb$^{-1}$, corresponding to 17 million of produced $η$'s from the $Φ\to ηγ$ radiative decay, have been analyzed to look for the C-violating decay $η\toγγγ$. The signal is searched in events with 4 photons in the final state by using the spectrum of the most energetic photon. The background is evaluated from the data themself, doing a fifth degree polynomial fit outside the signal region, and extrapolating inside it. No signal has been observed and taking into account a selection efficiency $ε= 20.3 %$ we get from a likelihood fit Br$(η\toγγγ) \le 1.6\times10^{-5}$ at 95% CL. The procedure has a systematic ambiguity at the 35 % level.

hep-ex↗
arXiv2003

The Trigger System of the ARGO-YBJ detector

The ARGO-YBJ experiment has been designed to detect air shower events over a large size scale and with an energy threshold of a few hundreds GeV. The building blocks of the ARGO-YBJ detector are single-gap Resistive Plate Counters (RPCs). The trigger logic selects the events on the basis of their hit multiplicity. Inclusive triggers as well as dedicated triggers for specific physics channels or calibration purposes have been developed. This paper describes the architecture and the main features of the trigger system.

hep-ex↗