Estimation of longitudinal bunch characteristics in the LHC using Schottky-based diagnostics

Lasocha, Kacper; Alves, D.

doi:10.1103/physrevaccelbeams.23.062803

Cited by 6 publications

(7 citation statements)

References 10 publications

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“…These finding are in accordance with those in other stochastic systems, e.g. the scaling of the average translation distance with the square root of the number of steps in a random walk [61] (where the average translation distance and the number of steps resemble the noise amplitude and the number of particles respectively) and the linear dependence of the noise power of synchrotron radiation on the number of particles in the bunch [57].…”

Section: Noise Power Dependence On Particle Volume and Number Of Particlessupporting

confidence: 91%

Noise Power Properties of Magnetic Nanoparticles as Measured in Thermal Noise Magnetometry

et al. 2021

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Magnetic nanoparticles have proven to be extremely useful in a broad range of biomedical applications. To ensure optimal efficiency, a precise characterization of these particles is required. Thermal Noise Magnetrometry (TNM) is a recently developed characterization technique that has already been validated against other techniques. TNM offers a unique advantage in that no external excitation of the system is required to drive the measurement. However, the extremely small stochastic signal in the fT range currently limits the accessibility of the method, and a better understanding of the influences of the sample characteristics on the TNM signal is necessary. In this study, we present a theoretical framework to model the magnetic noise power properties of particle ensembles and their signal as measured via TNM. Both intrinsic sample properties (such as the number of particles or their volume) and the geometrical properties of the sample in the setup have been investigated numerically and validated with experiments. It is shown that the noise power depends linearly on the particle concentration, quadratically on the individual particle size, and linearly on the particle size for a constant total amount of magnetic material in the sample. Furthermore, an optimized sample shape is calculated for the given experimental geometry and subsequently 3d printed, giving rise to an 3.5 fold increase in TNM signal from approximately 0.007 to 0.026 pT 2 with less than half of the magnetic material.

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Section: Noise Power Dependence On Particle Volume and Number Of Particlessupporting

confidence: 91%

Noise Power Properties of Magnetic Nanoparticles as Measured in Thermal Noise Magnetometry

et al. 2021

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“…Among the PyHEADTAIL input parameters described in figure 1, some are based on the fitting of the experimental spectrum as done in ref. [8,9] and allow to determine precise machine parameters of the specific fill we want to reproduce. The parameters based on this fitting procedure are horizontal and vertical tunes, horizontal and vertical chromaticities, synchrotron amplitude distribution and nominal synchrotron frequency.…”

Section: Experimental Benchmarkingmentioning

confidence: 99%

“…The fitting procedure of ref. [8] assumes that the synchrotron amplitudes 𝜏 follows a Rice distribution and provides the two parameters 𝜎 and 𝑏 of this distribution. On the other hand, the macro-particle simulation requires to have an initial distribution in terms of position 𝑧 and momentum deviation Δ𝑝.…”

Section: Experimental Benchmarkingmentioning

confidence: 99%

“…Figure 4 shows a comparison between the results of our proposed simulation-based method, the Monte Carlo method, the matrix formalism developed in refs. [8] and [9], and real measurements -7 -…”

Section: Theoretical Benchmarkingmentioning

confidence: 99%

“…However, for high-intensity LHC proton bunches, a quantitative and accurate interpretation of Schottky spectra can become more challenging due to the increased influence of beam-coupling impedance. Existing theoretical frameworks for Schottky spectrum reconstruction [1,8,9,11] do not account for impedance effects. This section investigates, both theoretically and through simulations, how the spectra are influenced by impedance, starting with the longitudinal case and subsequently exploring the transverse case.…”

Section: Beam-coupling Impedancementioning

confidence: 99%

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Impact of beam-coupling impedance on the Schottky spectrum of bunched beam

Lannoy,

Lasocha,

Pieloni

et al. 2024

J. Inst.

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The Schottky monitors of the Large Hadron Collider (LHC) can be used for non-invasive beam diagnostics to estimate various bunch characteristics, such as tune, chromaticity, bunch profile or synchrotron frequency distribution. However, collective effects, in particular beam-coupling impedance, can significantly affect Schottky spectra when large bunch charges are involved. In such conditions, the available interpretation methods are difficult to apply directly to the measured spectra, thus preventing the extraction of beam and machine parameters, which is possible for lower bunch charges. To study the impact of impedance on such spectra, we introduce a method for building Schottky spectra from macro-particle simulations performed with the PyHEADTAIL code, applied to LHC beam conditions. In this case, the use of a standard Fast Fourier Transform (FFT) algorithm to recover the spectral content of the beam becomes computationally intractable memory-wise, because of the relatively short bunch length compared to the large revolution period. To circumvent this difficulty, a semi-analytical method was developed to efficiently compute the Fourier transform. The simulated Schottky spectrum is then compared against theoretical formulas and measurements of Schottky signals previously obtained with lead ion beams in the LHC where impedance effects are expected to be limited. Furthermore, this study provides preliminary interpretations of the impact of beam-coupling impedance on proton Schottky spectra by incorporating longitudinal and transverse resonator-like impedance models into the simulations. A theoretical framework is also introduced for the case of the longitudinal impedance, allowing the extension of the existing theoretical formalism.

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