Harmonic Based Beam Position Measurements on Debunched Beams

In some accelerator environments, e.g. in linear accelerator (LINAC), the beam position is measured with a BPM operating at one particular strong harmonic component present in the beam signal. This approach has limitations once the beam gets debunched and the harmonic components drops. Nevertheless, from a signal processing point of view the signal-to-noise ratio can be still acceptable with highly debunched beams, leading, in principle, to a reasonable, even if degraded, position measurement. A simplified beam transport model developed for the CERN BI transfer line between LINAC4 and the PS Booster demonstrates, that in some case, the harmonic component cannot be used anymore for position measurement despite the fact it is still significative in amplitude

BPM Time of Flight Measurements for Setting-up the RF Cavities of the CERN Linac4

The newly constructed H$^-$ LINAC4 at CERN has recently completed its first extended reliability run. It is equipped with Beam Position Monitors (BPMs) based on shorted-stripline pick-up electrodes to measure both position and Time of Flight (ToF). The ToF, in turn used to calculate the kinetic energy of the beam, is determined through signal phase shift measurements between pairs of BPMs. ToF measurements are performed by scanning of the phase of the RF injected into the cavities to find the nominal RF settings for optimal beam acceleration. This paper focuses on the technical aspects of the ToF measurement as well as on the results obtained during beam commissioning and their comparison with beam dynamics simulations

New Beam Position Monitors for the CERN LINAC3 to LEIR Ion Beam Transfer Line

The ion injection line into the CERN Low Energy Ion Ring (LEIR) has recently been equipped with nine, new, electrostatic Beam Position Monitors (BPMs) in order to measure and optimize the trajectory of the low intensity ion beams coming from LINAC3. In this paper, we describe the design of the BPM, the low noise charge amplifier mounted directly on the BPM, and the digital acquisition system. There is special emphasis on the first commissioning results where the measured beam positions were seen to be perturbed by EMI and charging of the BPM electrodes by secondary particles. The effect of mitigation measures, including repelling voltages on the electrodes and external magnetic fields, are also discussed

Corporate Social Responsibility and Earnings Quality:International Evidence

ArticleIn this paper, we investigate whether the corporate social responsibility (CSR) orientation of a firm affects its reporting incentives, in terms of the trade-off between real earnings management (REM) and accrual-based earnings management (AEM). Furthermore, relying on previous literature on the relationship between legal enforcement and the trade-off between AEM and REM, we consider whether the CSR orientation plays a moderating role in this relationship. We base our study on a sample of 5,863 firm-year observations for 1,141 unique firms, covering 24 different countries over the period 2003–2009. We find that CSR-oriented firms are less likely to engage in REM than in AEM. Moreover, we document that in strong legal enforcement countries, incentives to use REM instead of AEM are significantly lower in companies with a high CSR orientation than in companies with a low CSR orientation. These findings are consistent with the expectation that CSR-oriented companies are less likely to engage in the more costly but harder to detect earnings management strategy, i.e. the strategy that alters the underlying real operations of the company (REM). We provide additional evidence for our arguments that CSR-oriented firms are more likely to give up REM than AEM because of its detrimental value on future performance. All together our evidence suggests that CSR orientation acts as a constraint for REM and in doing so it contributes to the creation of value for all stakeholders

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I conti delle aziende di Padova e della provincia con le analisi dei settori produttiv

Improvements on the LHC Interlock BPM system

The LHC interlock BPM system is used as part of the beam abort system to insure that beam trajectories in those regions are conform with a safe extraction of the beams from the main ring to the dump lines. After more than 10 years of operation, the system has shown some limitations in bandwidth and dynamic range and a study was initiated to look for improvements. Nowadays, with the availability of multi giga sample per second sampling rate ADC converters, there is poten-tial to greatly improve the performance of the system. In this paper a wideband architecture with direct acqui-sition of the BPM electrode signals, time interleaved on the same read-out channel is presented with emphasis on the design and construction of the critical components, and on the measured performance of a prototype system tested in the LHC during the 2022 run

Commissioning the New CERN Beam Instrumentation Following the Upgrade of the LHC Injector Chain

The LHC injectors Upgrade (LIU) program has been fully implemented during the second long shutdown (LS2), which took place in 2019-20. In this context, new or upgraded beam instrumentation was developed to cope with H⁻ beam in LINAC4 and the new Proton Synchrotron Booster (PSB) injection systems which would provide high brightness proton beams in the rest of the injector complex. After a short overview of the newly installed diagnostics, the main focus of this paper will move to the instruments already commissioned with the beam. This will include LINAC4 diagnostics, the PSB H⁰/H⁻ monitor, the PSB Trajectory Measurement System, and the PS beam gas ionization monitor. In addition, particular emphasis will be given to the first operational experience with the new generation of fast wire scanners installed in all injector synchronous

Beam Instrumentation for the CERN LINAC4 and PSB Half Sector Test

The construction, installation and initial commissioning of CERN's LINAC4 was completed in 2016 with H⁻ ions successfully accelerated to its top energy of 160 MeV. The accelerator is equipped with a large number of beam diagnostic systems that are essential to monitor, control and optimize the beam parameters. A general overview of the installed systems and their functional specifications will be followed by a summary of the most relevant results. This includes transverse profile monitors (wire scanners, wire grids and a laser profile monitor), beam position and phase monitors (whose ToF measurements were essential for adjusting RF cavity parameters), beam loss monitors, beam current transformers and longitudinal beam shape monitors. This contribution will also cover the beam instrumentation for the so-called PSB Half Sector Test, which has been temporarily installed in the LINAC4 transfer line to study H⁻ stripping efficiency. At this facility it was possible to test the new H⁰/H⁻ beam current monitor, designed to monitor the stripping efficiency and an essential element of the beam interlock system when the LINAC4 is connected to the PSB in 2019

Performance of the Low Energy Ion Ring at CERN with Lead Ions in 2022

2022 was a performance consolidation year for the Low Energy Ion Ring (LEIR) at CERN that demonstrated its capability of delivering the target beam parameters required for high luminosity production in the LHC in a reproducible and reliable way. The main steps that have led to the high performance reach of this beam, together with the machine stability improvements deployed, are detailed in this paper

Performance of the Low Energy Ion Ring at CERN with lead ions in 2022

2022 has been a performance consolidation year for the Low Energy Ion Ring (LEIR) at CERN that demonstrated its capability of delivering the target beam parameters required for high luminosity production in the LHC in a reproducible and reliable way. The main steps that have led to the high performance reach of this beam, together with the machine stability improvements deployed, are detailed in this paper