arXiv subjects

P. Prieto

Publications and source records attributed to P. Prieto.

At least 19 recordsLinked to original sources

arXiv2025

FPGA-Based Spill Regulation System for the Muon Delivery Ring at Fermilab

The Muon to Electron Experiment (Mu2e) requires a uniform beam profile from the Muon Delivery Ring to meet their experimental needs. A specialized Spill Regulation System (SRS) has been developed to help achieve consistent spill uniformity. The system is based on a custom-designed carrier board featuring an Arria 10 SoC, capable of executing real-time feedback control. The FPGA processes beam pulses of approximately 200 ns every 1.695 ${\mu}$s, allowing for continuous monitoring of the extracted spill intensity through fast bunch integration. The system directly controls three quadrupole magnets, which work in conjunction with sextupole magnets to achieve third-order resonant extraction. Furthermore, the board interfaces with Fermilab's Accelerator Control Network (ACNET), enabling operators to modify spill regulation settings in real-time via the control network while providing diagnostic waveforms. These waveforms help operators monitor the process and fine-tune the feedback mechanisms. This paper presents an overview of the board's architecture and its initial progress toward regulating beam extraction. This initial version of the regulation system aims to evaluate baseline performance to inform future system improvements.

physics.acc-ph↗

arXiv2023

Quantifying Li-content for compositional tailoring of lithium ferrite ceramics

Owing to their multiple applications, lithium ferrites are relevant materials for several emerging technologies. For instance, LiFeO2 has been spotted as an alternative cathode material in Li-ion batteries, while LiFe5O8 is the lowest damping ferrite, holding promise in the field of spintronics. The Li-content in lithium ferrites has been shown to greatly affect the physical properties, and in turn, the performance of functional devices based on these materials. Despite this, lithium content is rarely accurately quantified, as a result of the low number of electrons in Li hindering its identification by means of routine materials characterization methods. In the present work, magnetic lithium ferrite powders with Li:Fe ratios of 1:1, 1:3 and 1:5 have been synthesized, successfully obtaining phase-pure materials (LiFeO2 and LiFe5O8), as well as a controlled mixture of both phases. The powders have been compacted and subsequently sintered by thermal treatment (Tmax = 1100 {\deg}C) to fabricate dense pellets which preserve the original Li:Fe ratios. Li-content on both powders and pellets has been determined by two independent methods: (i) Rutherford backscattering spectroscopy combined with nuclear reaction analysis and (ii) Rietveld analysis of powder X-ray diffraction data. With good agreement between both techniques, it has been confirmed that the Li:Fe ratios employed in the synthesis are maintained in the sintered ceramics. The same conclusion is drawn from spatially-resolved confocal Raman microscopy experiments on regions of a few microns. Field emission scanning electron microscopy has evidenced the substantial grain growth taking place during the sintering process - mean particle sizes rise from about 600 nm in the powders up to 3.8(6) um for dense LiFeO2 and 10(2) um for LiFe5O8 ceramics.

cond-mat.mtrl-sci↗

arXiv2021

RBS/Channeling characterization of Ru(0001) and thin epitaxial Ru/Al$_2$O$_3$(0001) films

Thin epitaxial films of metals on insulating substrates are essential for many applications, as conducting layers, in magnetic devices or as templates for further growth. In this work, we report on the growth of epitaxial Ru films on single-crystalline Al$_2$O$_3$(0001) substrates by magnetron sputtering and their subsequent systematic characterization using Rutherford backscattering spectrometry of He ions both in random and in channeling conditions. We include results of a Ru(0001) single crystal for comparison. Analysis of channeling shows that films thicker than 35 nm grow with (0001) orientation, a well-defined epitaxial relation with the substrate and a high degree of crystal quality, comparable to the Ru(0001) single crystal. Thinner films of down to 7 nm in thickness, for which relaxation of epitaxial strain is not complete, produce a similar degree of dechanneling. The surface of the films can be prepared in a clean and ordered state in order to allow further epitaxial growth on top.

cond-mat.mtrl-sci↗

arXiv2021

Submacropulse electron-beam dynamics correlated with higher-order modes in a Tesla-type cryomodule

Experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility to elucidate the effects of long-range wakefields (LRWs) in TESLA-type superconducting rf cavities. In particular, we investigated the higher-order modes (HOMs) generated in the eight cavities of a cryomodule (CM) due to off-axis steering with correctors located ~4 m upstream of the CM. We have observed correlated submacropulse centroid slews of a few-hundred microns and centroid oscillations at ~240 kHz in the rf BPM data after the CM. The entrance energy into the CM was 25 MeV, and the exit energy was 100 MeV with 125 pC/b and 400 pC/b in 50-bunch pulse trains. These experimental results were evaluated for machine learning training aspects which will be used to inform the commissioning plan for the Linac Coherent Light Source-II injector CM.

physics.acc-ph↗

arXiv2021

LCLS-II-HE verification cryomodule high gradient performance and quench behavior

An 8-cavity, 1.3 GHz, LCLS-II-HE cryomodule was assembled and tested at Fermilab to verify performance before the start of production. Its cavities were processed with a novel nitrogen doping treatment to improve gradient performance. The cryomodule was tested with a modified protocol to process sporadic quenches, which were observed in LCLS-II production cryomodules and are attributed to multipacting. Dedicated vertical test experiments support the attribution to multipacting. The verification cryomodule achieved an acceleration voltage of 200 MV in continuous wave mode, corresponding to an average accelerating gradient of 24.1 MV/m, significantly exceeding the specification of 173 MV. The average Q0 (3.0x10^10) also exceeded its specification (2.7x10^10). After processing, no field emission was observed up to the maximum gradient of each cavity. This paper reviews the cryomodule performance and discusses operational issues and mitigations implemented during the several month program.

physics.acc-ph↗

arXiv2018

Submacropulse Electron-Beam Dynamics Correlated With Higher-Order Modes In Tesla-Type Superconducting RF Cavities

We report the direct observations of sub-macropulse beam centroid oscillations correlated with higher order modes (HOMs) which were generated by off-axis electron beam steering in TESLA-type superconducting RF cavities. The experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility using its unique configuration of a photocathode rf gun injecting beam into two separated 9-cell cavities in series with corrector magnets and beam position monitors (BPMs) located before, between, and after them. Oscillations of ~100 kHz in the vertical plane and ~380 kHz in the horizontal plane with up to 600-{\mu}m amplitudes were observed in a 3-MHz micropulse repetition rate beam with charges of 100, 300, 500, and 1000 pC/b. However, the effects were much reduced at 100 pC/b. The measurements were based on HOM detector circuitry targeting the first and second dipole passbands, rf BPM bunch-by-bunch array data, imaging cameras, and a framing camera. Calculations reproduced the oscillation frequencies of the phenomena in the vertical case. In principle, these fundamental results may be scaled to cryomodule configurations of major accelerator facilities.

physics.acc-ph↗

arXiv2018

Commissioning And First Results From The Fermilab Cryomodule Test Stand

A new test stand dedicated to Superconducting Radiofrequency (SRF) cryomodule testing, CMTS1, has been commissioned and is now in operation at Fermilab. The first device to be cooled down and powered in this facility is the prototype 1.3 GHz cryomodule assembled at Fermilab for LCLS-II. We describe the demonstrated capabilities of CMTS1, report on steps taken during commissioning, provide an overview of first test results, and survey future plans.

physics.acc-ph↗

arXiv2018

Diagnostics upgrades for investigations of HOM effects in Tesla-type SCRF cavities

We describe the upgrades to diagnostic capabilities on the Fermilab Accelerator Science and Technology (FAST) electron linear accelerator that will allow investigations of the effects of high-order modes (HOMs) in SCRF cavities on macropulse-average beam quality. We examine the dipole modes in the first pass-band generally observed in the 1.6-1.9 GHz regime for TESLA-type SCRF cavities due to uniform transverse beam offsets of the electron beam. Such cavities are the basis of the accelerators such as the European XFEL and the proposed MaRIE XFEL facility. Preliminary HOM detector data, prototype BPM test data, and first framing camera OTR data with ~20 micron spatial resolution at 250 pC per bunch will be presented.

physics.acc-ph↗

arXiv2018

Commissioning and first results of the Electron Beam Profiler in the Main Injector at Fermilab

The planned neutrino program at Fermilab requires large proton beam intensities in excess of 2 MW. Measuring the transverse profiles of these high intensity beams is challenging and often depends on non-invasive techniques. One such technique involves measuring the deflection of a probe beam of electrons with a trajectory perpendicular to the proton beam. A device such as this is already in use at the Spallation Neutron Source at ORNL and a similar device has been installed in the Main Injector at Fermilab. Commissioning of the device is in progress with the goal of having it operational by the end of the year. The status of the commissioning and initial results will be presented.

physics.acc-ph↗

arXiv2016

Cross sections of X-ray production induced by C and Si ions with energies up to 1 MeV/u on Ti, Fe, Zn, Nb, Ru and Ta

X-ray production differential cross sections induced by C and Si ions with energies from 1 MeV/u down to 0.25 MeV/u, produced by the CMAM 5 MV tandem accelerator, have been measured for thin targets of Ti, Fe, Zn, Nb, Ru and Ta in a direct way. X-rays have been detected by a fully characterized silicon drift diode and beam currents have been measured by a system of two Faraday cups. Measured cross sections agree in general with previously published results. The ECPSSR theory with the united atoms correction gives absolute values close to the experimental ones for all the studied elements excited by C ions and for Ta, Nb and Ru excited by Si ions. For Ti, Fe and Zn excited by Si, the basic ECPSSR theory gives better agreement, although on absolute values the gap for Ti is still large.

physics.atom-ph↗

arXiv2015

Installation status of the electron beam profiler for the Fermilab Main Injector

The planned neutrino program at Fermilab requires large proton beam intensities in excess of 2 MW. Measuring the transverse profiles of these high intensity beams is challenging and often depends on non-invasive techniques. One such technique involves measuring the deflection of a probe beam of electrons with a trajectory perpendicular to the proton beam. A device such as this is already in use at the Spallation Neutron Source at ORNL and the installation of a similar device is underway in the Main Injector at Fermilab. The present installation status of the electron beam profiler for the Main Injector will be discussed together with some simulations and test stand results.

physics.acc-ph↗

arXiv2014

First Operation of an Ungated Diamond Field-Emission Array Cathode in a L-Band Radiofrequency Electron Source

We report on the first successful operation of a field-emitter-array cathode in a conventional L-band radio-frequency electron source. The cathode consisted of an array of $\sim 10^6$ diamond diamond tips on pyramids. Maximum current on the order of 15~mA were reached and the cathode did not show appreciable signs of fatigue after weeks of operation. The measured Fowler-Nordheim characteristics, transverse beam density, and current stability are discussed. Numerical simulations of the beam dynamics are also presented.

physics.acc-ph↗

arXiv2013

Test Results of Tesla-Style Cryomodules at Fermilab

Commissioning and operation of the first Tesla-style Cryomodule (CM-1) at Fermilab was concluded in recent months. A second Tesla Type III+ module, RFCA002, will be replacing it. CM-1 is the first 8-cavity ILC style cryomodule to be built at Fermilab and also the first accelerating cryomodule of the Advanced Superconducting Test Accelerator (ASTA). We report on the operating results of both of these cryomodules.

physics.acc-ph↗

arXiv2012

Tevatron Beam Position Monitor Upgrade

This paper describes the development of a digital-based Beam Position System which was designed, developed, and adapted for the Tevatron during Collider Run II.

physics.acc-ph↗

arXiv2012

A Wire Position Monitor System for the 1.3 GHZ Tesla-Style Cryomodule at the Fermilab New-Muon-Lab Accelerator

The first cryomodule for the beam test facility at the Fermilab New-Muon-Lab building is currently under RF commissioning. Among other diagnostics systems, the transverse position of the helium gas return pipe with the connected 1.3 GHz SRF accelerating cavities is measured along the ~15 m long module using a stretched-wire position monitoring system. An overview of the wire position monitor system technology is given, along with preliminary results taken at the initial module cool down, and during further testing. As the measurement system offers a high resolution, we also discuss options for use as a vibration detector.

physics.acc-ph↗

arXiv2012

High Resolution BPM Upgrade for the ATF Damping Ring at KEK

A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and processing, and also implements a new automatic gain error correction schema. The technical concept and realization as well as results of beam studies are presented.

physics.acc-ph↗

arXiv2012

RF Test Results from Cryomodule 1 at the Fermilab SRF Beam Test Facility

Powered operation of Cryomodule 1 (CM-1) at the Fermilab SRF Beam Test Facility began in late 2010. Since then a series of tests first on the eight individual cavities and then the full cryomodule have been performed. We report on the results of these tests and lessons learned which will have an impact on future module testing at Fermilab.

physics.acc-ph↗

arXiv2008

Operational aspects of the Main Injector large aperture quadrupole (WQB)

A two-year Large Aperture Quadrupole (WQB) Project was completed in the summer of 2006 at Fermilab. Nine WQBs were designed, fabricated and bench-tested by the Technical Division. Seven of them were installed in the Main Injector and the other two for spares. They perform well. The aperture increase meets the design goal and the perturbation to the lattice is minimal. The machine acceptance in the injection and extraction regions is increased from 40pi to 60pi mm-mrad. This paper gives a brief report of the operation and performance of these magnets.

physics.acc-ph↗