The dipole mode synchrotron frequency is a basic beam parameter; it and a few similarly basic quantities measured at small time intervals serve to characterize the longitudinal beam dynamics throughout the acceleration cycle. The effective accelerating voltage, in conjunction with the amount of rf voltage required for the acceleration, is important for the estimate of the beam energy loss per turn. The dipole mode frequency can be used to obtain the effective accelerating rf voltage, providing that it can be measured precisely. The synchrotron frequency measured from the synchrotron phase detector signal (SPD) generally agrees well with calculation, and it can be applied for such purposes as inferring the effective rf voltage.
For booster synchrotrons, like the SIS at GSI, space charge is one of the main intensity limitations. At injection energy the space charge induced tune spreads in booster synchrotrons are large, reaching up to 0.5 and the ramping times are typically short. We study the effect of several localized electron lenses distributed equally around the circumference in order to compensate for the transverse space charge force.
The synchrotron motion simulator is invented to simulate the longitudinal motion for particles under RF (Radio Frequency) voltage field in a ring accelerator. It is especially used to study the efficiency of adiabatic capture for a booster ring. The purpose of adiabatic capture is to optimize RF voltage settings during the ramping of beam energy and obtain the greatest efficiency of particle capture. In this paper we study the longitudinal (synchrotron) motion for particles in the TLS (Taiwan Light Source) booster. We compare the properties of TLS booster as a proton or electron accelerator, u…
It is important to have experimental methods to estimate the maximum beam intensity for the Fermilab Booster as objective input into long term program commitments. An important existing limit is set by the available rf power. This limit is difficult to set a priori because the real longitudinal impedance is not well known. The synchrotron phase at transition crossing was measured using both the mountain range plot and the direct phase measurement of the RF accelerating voltage relative to the beam, and results were consistent. They were applied to predict 6E12 maximum Booster beam intensity wi…
The Fermilab Booster is a fast ramping (15Hz) synchrotron which accelerates protons from 400MeV to 8GeV. During commissioning of a transverse digital damper system, it was shown that the damper could provide a measurement of the machine tune throughout the cycle by exciting just 1 of the 84 bunches with minimal impact on the machine operation. The algorithms used to make the measurement have been incorporated into the damper FPGA firmware allowing for real-time tune monitoring of all Booster cycles.
The Future Circular Collider (FCC) study investigates the feasibility of circular colliders in the post-LHC era. The sub-study FCC-ee is a 100 km electron positron collider in the energy range of 90-365 GeV. In order to achieve a design luminosity in the order of $10^{36}$cm$^{-2}$s$^{-1}$ continuous top-up injection is required. The injector chain therefore includes a 100 km booster synchrotron in the same tunnel as the collider rings. This paper presents the lattice design of this booster synchrotron and the first dynamic aperture studies based on the chromaticity correction sextupole scheme…
The timing system of SPring-8 booster synchrotron generates various timing signals concerning beam injection, acceleration from 1 GeV to 8 GeV and ejection. We have improved the timing system of the synchrotron giving it better stability and flexibility. This improvement results the other merits of advanced operations, for example, storing electron beam in the synchrotron, changing the injection cycle from 1 Hz to the slower frequency to increase the RF knock-out (RF-KO) operation period and ejecting the low energy beam during ramping up.
Detrimental beam dynamics effects limit performance of high intensity rapid cycling synchrotrons (RCS) such as the 8 GeV proton Fermilab Booster. Here we report the results of comprehensive experimental studies of various beam intensity dependent effects in the Booster. In the first part, we report the dependencies of the Booster beam intensity losses on the total number of protons per pulse and on key operational parameters such as the machine tunes and chromaticities. Then we cross-check two methods of the beam emittance measurements (the multi-wires proportional chambers and the ionization …
ANKA is a 2.5 GeV synchrotron radiation storage ring under construction at the Forschungszentrum Karlsruhe in Germany. The injector system will consist of a pre-injector with an end energy of 20 to 50 MeV and a 0.5 GeV booster synchrotron. In the following three different concepts for designing the booster synchrotron are compared.
A new beam dump has been designed, built, installed and operated to withstand the future proton beam extracted from the Proton Synchrotron Booster (PSB) in the framework of the LHC Injector Upgrade (LIU) Project at CERN, consisting of up to 1E14 protons per pulse at 2 GeV, foreseen after the machine upgrades planned for CERN's Long Shutdown 2 (2019-2020). In order to be able to efficiently dissipate the heat deposited by the primary beam, the new dump was designed as a cylindrical block assembly, made out of a copper alloy and cooled by forced airflow. In order to determine the energy density …
Fermilab Booster synchrotron requires an intensity upgrade from 4.5x1012 to 6.5x1012 protons per pulse as a part of Fermilabs Proton Improvement Plan-II (PIP-II). One of the factors which may limit the high-intensity performance is the fast transverse instabilities caused by electron cloud effects. According to the experience in the Recycler, the electron cloud gradually builds up over multiple turns in the combined function magnets and can reach final intensities orders of magnitude greater than in a pure dipole. Since the Booster synchrotron also incorporates combined function magnets, it is…
The match between the Linac beam energy and the energy determined by the bending field of the Booster magnets is crucial for rf capture, beam quality, and the transmission efficiency in a Booster cycle. The observation of the injection energy match is important for injection tuning. Several signals, such as phase shift drive (PSD), radial position error (RPOS), synchrotron phase (SPD), and fast phase error (FPERR), provide consistent information on the energy match and can be used for a injection match tuning.
A proof-of-principle experimental setup for the extraction of 6 GeV electrons from the DESY II Booster Synchrotron using the channeling effect in a bent crystal is elaborated. Various aspects of the experimental setup were investigated in detail, such as the particle beam dynamics during the extraction process, the manufacturing and characterization of bent crystals, and the detection of the extracted beam. In order to optimize the crystal geometry, the overall process of beam extraction was simulated, taking into account the influence of radiation energy losses. As result it is concluded that…
The CERN FCC-ee top-up booster synchrotron will accelerate electrons and positrons from an injection energy of 20 GeV up to an extraction energy between 45.6 GeV and 182.5 GeV depending on the operation mode. These accelerated beams will be used for the initial filling of the high-luminosity FCC-ee collider and for keeping the beam current constant over time using continuous top-up injection. Due to the high-intensities of the circulating beams, collective effects may represent a limitation in the top-up booster. In this work we present a first evaluation of the impedance model and the effects…
The present Fermilab proton Booster is an early example of a rapidly-cycling synchrotron (RCS). Built in the 1960s, it features a design in which the combined-function dipole magnets serve as vacuum chambers. Such a design is quite cost-effective, and it does not have the limitations associated with the eddy currents in a metallic vacuum chamber. However, an important drawback of that design is a high impedance, as seen by a beam, because of the magnet laminations. More recent RCS designs (e.g. J-PARC) employ large and complex ceramic vacuum chambers in order to mitigate the eddy current effec…
The bunch-by-bunch BPM signal array has to be reshaped into a turn-by-turn (TBT) matrix in order to make the TBT beam position information of a single bunch available for further data analysis, such as via the Fourier transform to obtain the synchrotron tune and betatron tune, etc. Since the RF frequency sweeps more than 10 MHz in the first 8 ms of a Booster cycle, the revolution time decreases more than 20%. The number of data points for each Booster turn (BT) should be varied in the same pace with the revolution time since the sampling rate of a digital oscilloscope is usually fixed. And thi…
Increasing proton beam power on neutrino production targets is one of the major goals of the Fermilab long term accelerator programs. In this effort, the Fermilab 8 GeV Booster synchrotron plays a critical role for at least the next two decades. Therefore, understanding the Booster in great detail is important as we continue to improve its performance. For example, it is important to know accurately the available RF power in the Booster by carrying out beam-based measurements in order to specify the needed upgrades to the Booster RF system. Since the Booster magnetic field is changing continuo…
The Fermilab Proton Source machines, constituted by Pre-Injector, conventional Linac and Booster synchrotron, at Fermi National Accelerator Laboratory (Fermilab) had have a long history of successful beam operations. Built in late '60s, the Fermilab Proton Source began operations early in the '70s and since then it has successful provided protons to support the laboratory physics experiments. During the past decade, Booster performance reached unprecedented proton flux delivery of the order of 1.0-1.1E17 protons per hour, corresponding to 40 kW of beam power while maintained an allowed upper l…
In synchrotron machines, the beam extraction is accomplished by a combination of septa and kicker magnets which deflect the beam from an accelerator into another. Ideally the kicker field must rise/fall in between the beam bunches. However, in reality, an intentional beam-free time region (aka "notch") is created on the beam pulse to assure that the beam can be extracted with minimal losses. In the case of the Fermilab Booster, the notch is created in the ring near injection energy by the use of fast kickers which deposit the beam in a shielded collimation region within the accelerator tunnel.…
A longitudinal beam properties, data acquisition system has been commissioned to operate in the Fermilab booster ring. This system captures real time information including beam synchronous phase, bunch length, and coupled bunch instability amplitudes as the beam is accelerated from 400 MeV to 8 GeV in 33 ms. The system uses an off-the-shelf Tektronix oscilloscope running Labview software and a synchronous pulse generator. This paper describes the hardware configuration and the software configuration used to optimize the data processing rate.
The 40-year-old Fermilab Proton Source machines, constituted by the Pre-Injector, Linac and the synchrotron Booster, have been the workhorse of the Fermi National Accelerator Laboratory (Fermilab). During this time, the High Energy Physics Program has demanded an increase in proton throughput, especially during the past decade with the beginning of the neutrino program at Fermilab. In order to achieve a successful program, major upgrades and changes were made in Booster. Once again, the Proton Source has been charged to double their beam throughput, while maintain the present residual activati…
Integrable optics is an innovation in particle accelerator design that enables strong nonlinear focusing without generating parametric resonances. We use the Synergia tracking code to investigate the application of integrable optics to high-intensity hadron rings. We consider an integrable rapid-cycling synchrotron (iRCS) designed to replace the Fermilab Booster. We find that incorporating integrability into the design suppresses the beam halo generated by a mismatched KV beam. Our iRCS design includes other features of modern ring design such as low momentum compaction factor and harmonically…
The completion of the PIP-II project and its superconducting linear accelerator will provide up to 1.2 MW of beam power to the LBNF/DUNE facility for neutrino physics. It will also be able to produce high-power beams directly from the linac that can be used for lower-energy particle physics experiments as well, such as directing beam toward the Muon Campus at Fermilab for example. Any further significant upgrade of the beam power to DUNE, however, will be impeded by the limitations of the present Booster synchrotron at the facility. To increase the power to DUNE by a factor of two would requir…
The FNAL accelerator complex is poised to reach MW neutrino beams on target for the exploration of the dark sector physics and rare physics program spaces. Future operations of the complex will include CW linac operations at beam intensities that have not been seen before \cite{PIP2,RCS_LOI}. The ambitious beam program relies on multi-turn H$^{-}$ injection into the FNAL Booster and then extracted into delivery rings or the Booster Neutrino Beam (BNB) 8 GeV HEP program. A new rapid-cycling synchrotron (RCS) will be required to reach the LBNF goal of 2.4 MW because of intense space-charge limit…
Electric current fluctuations are one type of unavoidable machine imperfections,and induce magnetic-field perturbations as a source of instabilities in accelerators. This paper presents measurement-based methodology of modeling the fluctuating electric current arising from the power system of Fermilab's Booster synchrotron to discuss the ramifications of the presence of ripple current and space-charge defocusing effects. We also present the method of generating stochastic noise and the measurement and analysis methods of ripple current and offending electromagnetic interferences residing in th…
To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energy RHIC electron Cooler (LEReC) is currently under commissioning at BNL. The Linac of LEReC is designed to deliver a 1.6 MeV to 2.6 MeV electron beam, with rms dp/p less than 5e-4. A 704 MHz superconducting radio frequency (SRF) booster cavity in this Linac provides up to 2.2 MeV accelerating voltage. With such a low energy and very demanding energy spread requirement, control of Higher Order Modes (HOMs) in the cavities becomes critical and needs to be carefully evaluated to ensure minimum impact on the b…
Tune identification - i.e. attribution of the spectral peak to a particular normal mode of oscillations - can present a significant difficulty in the presence of strong transverse coupling when the normal mode with a lower damping rate dominates spectra of Turn-by-Turn oscillations in both planes. The introduced earlier phased sum algorithm helped to recover the weaker normal mode signal from the noise, but by itself proved to be insufficient for automatic peak identification in the case of close phase advance distribution in both planes. To resolve this difficulty we modified the algorithm by…
Below we summarize presentations, discussions and general conclusions of the Workshop session on "Beam Dynamics Issues". Major subjects include effects due to synchrotron radiation (SR), cryogenic loads, electron cloud, impedances, intra-beam scattering (IBS) and beam-beam interactions.
The build up of electron clouds inside a particle accelerator vacuum chamber can produce strong transverse and longitudinal beam instabilities which in turn can lead to high levels of beam loss often requiring the accelerator to be run below its design specification. To study the behaviour of electron clouds at the ISIS Proton Synchrotron, a Micro-Channel Plate (MCP) based electron cloud detector has been developed. The detector is based on the Retarding Field Analyser (RFA) design and consists of a retarding grid, which allows energy analysis of the electron signal, and a MCP assembly placed …
We reinvestigate the gravitational waves (GWs) induced by charged particles in storage rings. There are two major components in such GWs. One is the gravitational synchrotron radiation (GSR), i.e., the direct emission by the bending of the trajectory of a relativistic charged particle, much like the conventional electromagnetic synchrotron radiation (EMSR), albeit with characteristic difference in their radiation spectra. While the conventional EMSR spectrum peaks at the critical frequency, $ω_c=γ^3ω_0\ggω_0$, the spectrum of GSR peaks at the storage ring fundamental frequency $ω_0$, which is …
A novel polarimeter based on the asymmetry in the spacial distribution of synchrotron radiation will make for a fine addition to the existing Møller and Compton polarimeters. The spin light polarimeter consists of a set of wiggler magnet along the beam that generate synchrotron radiation. The spacial distribution of synchrotron radiation will be measured by ionization chambers. The up-down (below and above the wiggle) spacial asymmetry in the transverse plain is used to quantify the polarization of the beam. As a part of the design process, effects of a realistic wiggler magnetic field and an …
