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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Commissioning results of the BNL Alternating Gradient Synchrotron booster AC dipole

Here, an AC dipole has been installed in the AGS booster as part of polarized beam developments for the future Electron Ion Collider (EIC). This will allow preserving helion beam polarization through two intrinsic resonances during acceleration to an energy corresponding to |$Gγ$| = 10.5. AC dipoles can preserve polarization by forcing the beam to undergo large amplitude vertical betatron oscillations. These coherent oscillations cause all particles to sample the strong horizontal fields of quadrupoles, and result in a full spin flip. In preparation for the AC dipole being used for polarized helions, it was first commissioned with polarized protons. The proton extraction energy was raised to allow protons to cross $Gγ$ = 0 + $v_y$ = 4.8087. As an artifact of the experiment using polarized protons, the booster settings for bunch extraction interfered with the coherent oscillations and limited the maximum coherent amplitude. This interference will be well separated in the case of polarized helions. Polarized protons crossed the $Gγ$ = 0 + $v_y$ intrinsic resonance with a full spin flip through use of the AC dipole. Simulations of the resonance crossing using Zgoubi accurately predict the polarization relative to the coherent amplitude.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

On the Possibility of Installing the Rapid Cycling Synchrotron of the Electron Ion Collider in the AGS Tunnel

This report describes electron injector concepts for the Electron Ion Collider (EIC) using the tunnel of the Alternating Gradient Synchrotron (AGS) of Brookhaven National Laboratory which is to be compared to the RCS in the RHIC tunnel or a new ring in a new tunnel. Possible designs of the electron booster synchrotron, the Rapid Cycling Synchrotron (RCS) with good spin transparency with electron energies of up to 10 GeV and 18 GeV and placing the injector linac in the adjacent Building 912 for are worked out. The main reason for studying such options is the expectation that it will reduce the Electron Ion Collider injector cost because no civil construction is required, the machine is very compact, and existing infrastructure can be used. The design of an RCS with a top energy of 10 GeV with good spin transparency is quite conventional. However, for collider operation with 18 GeV electrons, this option would require accelerating the 10 GeV beam in the Electron Storage Ring (ESR) to 18 GeV and relying on the Sokolov Ternov self-polarization at 18 GeV in the ESR. Solutions for an RCS with Electron energies of up to 18 GeV with or without spin transparency are found to be possible but push the envelope of conventional magnet technology.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Computation of magnetic fields from field components on a plane grid

An algorithm is presented to calculate the field components of the magnetic field [B x (x, y, z), B y (x, y, z), B z (x, y, z)] at a point (x, y, z) in space, from the knowledge of the components [B x (x, y) = 0, z), B y (x, y = 0, z), B z (x, y = 0,z)] on a “reference plane”, which is normal to the y-axis at . The algorithm, which is a general one and is not restricted to fields with mid-plane symmetry is based on the Maclaurin series expansion of the magnetic field components at any point in space in terms of the distance (y) of the point from the reference plane. The coefficients of the Maclaurin series expansion are expressed in terms of the on-plane field components and their partial derivatives with respect to spatial coordinates (). The field components are usually generated from magnetic field measurements on a rectangular grid on the plane. This algorithm was employed in 1986 in the RAYTRACE computer code to help calculate the optical properties of magnets and of the Alternating Gradient Synchrotron (AGS) at the Brookhaven National Laboratory (BNL). Here, a general mathematical formulation of this algorithm based on the differential algebraic method was presented by Makino in 2011. This paper presents the step by step derivation of the algorithm and provides the necessary formulas to be introduced by the reader in any computer code which requires the field components generated by magnetic devices. In addition provides an example of the use of the algorithm and its limitations as applied to a Halbach type magnet with or without median plane symmetry.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

A state of the art Lambertson septum magnet of the RHIC beam injection system

The beam injection system of the Relativistic Heavy Ion Collider (RHIC) is the last section of the beam transfer line which transports the beam from the Alternating Gradient Synchrotron (AGS) to RHIC and comes under the acronym AtR (AGS to RHIC). The Lambertson septum magnet is one of the magnetic elements of the RHIC injection system. This paper presents results from the 2D and 3D electromagnetic design of the RHIC Lambertson septum magnet which has unique design features to minimize the magnetic field at the circulated beam region including the fringe field regions at the entrance and exit of the magnet.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Optimizing injection for the storage ring proton-EDM experiment

The proposed proton electric dipole moment (pEDM) experiment at Brookhaven National Laboratory (BNL), to be built inside the alternating gradient synchrotron (AGS) tunnel, aims to measure the proton’s electric dipole moment with a sensitivity of 10 −29 𝑒 cm. This paper presents the design of the injection line from the AGS booster to the pEDM storage ring, utilizing portions of the existing booster-to-AGS (BtA) transfer line. Building on the symmetric-hybrid lattice design [, Comprehensive symmetric-hybrid ring design for a proton-EDM experiment at below 10 −29 𝑒 cm, Phys. Rev. D 105, 032001 (2022)], our study emphasizes rigorous optics matching, detailed particle and spin tracking, and systematic error mitigation essential for achieving a target sensitivity of 10 −29 𝑒 cm. This design preserves the proton’s vertical spin orientation within ±20 mrad, a critical requirement for the pEDM measurement. Particle and spin tracking simulations using the ray-tracing code Zgoubi [F. Méot, Zgoubi users’ guide, Technical Report, Brookhaven National Laboratory (BNL), Relativistic Heavy Ion Collider (RHIC), Upton, NY, 2012] validate the design’s performance, demonstrating its feasibility for this precision experiment. The simulation results demonstrate that both clockwise (CW) and counterclockwise (CCW) injection lines meet the stringent beam envelope and polarization requirements.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Reevaluating linear accelerator shielding for 320 µA of proton beam

The collider-accelerator facilities at Brookhaven National Laboratory (BNL) have been developing since the completion of the experiments they were originally built for, and their uses for research have evolved over the years with a variety of users. With these changes, we must be careful to avoid potential radiation hazards of worst-case scenarios, although these faults are unlikely. One of these changes in the Collider-Accelerator Department (C-AD) is the replacement of power supplies and upgrading the linear accelerator (Linac) radiofrequency system to allow the Brookhaven Linac Isotope Producer (BLIP) to use a 320 μA average current. This current of 320 μA is greater than any current that the Linac shielding has withstood before, and thus this project in reevaluating the Linac shielding is necessary to ensure all future Linac research is conducted safely. Particularly, this project aims to estimate the radiation doses in the Alternating Gradient Synchrotron (AGS) tunnel near the Linac tunnel and in the equipment bay room near the gate valve of the last tank (tank 9) of Linac. To do this, we used the particle transport code, Monte Carlo N-Particle 6.2 (MCNP6.2), to perform the simulation and model the facilities of Linac and AGS at BNL. This simulation allowed us to investigate the extent of radiation dose rates in various areas of the facilities by placing detectors in specific locations. We could therefore determine whether the dose rates due to these faults is acceptable for limits set by the Department of Energy (DOE) and BNL, and if the shielding is sufficient.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Highlights from BNL and RHIC 2016

The Relativistic Heavy Ion Collider (RHIC) was designed and built at Brookhaven National Laboratory (BNL) and is one of the two remaining operating hadron colliders in the world, the other being the CERN LHC. There were also several previous facilities at BNL including the 30 GeV Alternating Gradient Synchrotron (AGS–now the RHIC injector) where the muon-neutrino, and CP violation were discovered and the 3 GeV Cosmotron where the $K^0_2$ was discovered. There have been many other discoveries at BNL.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

A skew quadrupole for the AGS to minimize the polarization losses of the polarized beams

The partial helices installed in the Alternating Gradient Synchrotron (AGS) 9 [1] eliminate both, the imperfection and the vertical intrinsic spin resonances thus yielding a 70% polarized proton beam with rigidity 79.4 [Tm] with 2x10 11 protons/bunch at the end of the AGS acceleration cycle. The initial beam polarization at the exit of the 200 MeV Linac is measured to be 80%. The 10% loss of the polarization at the end of the AGS acceleration cycle is due to the horizontal spin resonances which are caused by the betatron oscillations of the beam in the presence of the partial helices. To reduce the effect of these horizontal spin resonances on the beam polarization, the “jump Quads method” is applied in the AGS [2] which eliminates, almost all, the horizontal spin resonances and increases the final polarization of the proton beam to the value of 70%. A study [3] shows that these horizontal spin resonances can be totally eliminated by introducing into the AGS ring, skew quadrupoles which linearly couple the beam motions to excite new horizontal spin resonances which minimize the horizontal-spin-resonances caused by the partial-helices.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Improvements to Stripping Foils in BTA

To achieve the desired charge state in the Alternating Gradient Synchrotron (AGS), there is a stripping foil in the Booster to AGS (BtA) transfer line. For light ions, such as p, d, and h, they are already fully stripped in the Booster, or ions such as O have few electrons to be stripped off, and a thin foil of aluminum is used. For medium weight ions, such as Zr and Ru, they use what foils are available which have been optimized for heavy and light ions at 100 MeV/u. This worked well in the Zr case which achieved a measured stripping efficiency of 87%, contrary to the Ru case which achieved a measured stripping efficiency of 63%. For the EIC early science, Ag is currently intended to be the first ion. Using our existing foils, this would, at best, yield a helium-like charge state with a theoretical stripping efficiency of 50%. To improve on this, two foils of Ti or Nb have been selected to provide optimal stripping efficiency of Ag, and other energetic medium ions, which can reach 90% efficiency to fully strip the Ag ions. For heavy ions, the Al+C or Al+Ni stripping foils (sandwich foils) are used to produce helium-like charge states. For high intensity operation of Au, the Al foil nears its melting point and, in some cases, has been severely damaged. To maximize foil lifetime, there is a maximum intensity per unit time in BTA dependent on the Booster and AGS timing configurations. To mitigate the risk of melting the Al, replacement foils that use Ti, Nb, or anodized Al have been evaluated for their improved thermal qualities. At the selected thicknesses, each foil has equivalent charge distributions before entering the C foil, and should provide the same stripping efficiency through the entire sandwich.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Rematching AGS Booster synchrotron injection lattice for smaller transverse beam emittances

The polarized proton beam is injected into the booster via the charge-exchange (H- to H+) scheme. The emittance growth due to scattering at the stripping foil is proportional to the beta functions at the foil. It was demonstrated that the current scheme of reducing the beta functions at the stripping foil preserves the emittance better; however the betatron tunes are above but very close to half integer. Due to concern of space charge and half integer in general, options of lattice designs aimed towards reducing the beta functions at the stripping foil with tunes at more favorable places are explored.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

FFA BEAM TRANSPORT DEMONSTRATION DEVELOPMENT FOR THE CEBAF 22 GeV UPGRADE

Jefferson Lab is planning an upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) to deliver highly polarized electron beams up to 22 GeV using Fixed- Field Alternating-gradient (FFA) magnets. As the application of FFA technology in the 10–22 GeV energy range is unprecedented, experimental validation is required prior to full-scale implementation. To support this effort, a dedicated FFA test insert is proposed within the existing CEBAF infrastructure, with candidate locations in the Beam Switchyard (BSY) dump line or the Hall C beamline. The testbed will consist of a half or full FFA cell using combined-function permanent magnets and will enable systematic studies of beam transport, field quality, alignment, and magnet performance under realistic conditions. Operation with polarized beams in the 5–11 GeV range will closely replicate the energy scaling of the full upgrade. This paper presents the current design status and layout options for the proposed FFA beam transport test line.

Ogur, S. [Thomas Jefferson National Accelerator Fa↗
DOE OSTI2016

Run 16, eIPM Summary

Three problems with the eIPMs were corrected during the 2015 summer shutdown. These involved ac coupling and 'negative profiles', detector 'dead zone' created by biasing, and gain control on ramp. With respect to Run 16, problems dealt with included gain depletion on horizontal MCP and rf pickup on profile signals; it was found that the MCP was severely damaged over part of the aperture. Various corrective measures were applied. Some results of these measured obtained during Run 16 are shown. At the end of Run 16 there was a three-­day beam run to study polarized proton beams in the AGS. Attempts to minimize beam injection errors which increase emittance by using the eIPMs to measure the contribution of injection mismatch to the AGS output beam emittance are recounted. .

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Overview and analysis of the 2016 Gold Run in the Booster and AGS

Run 16 differed from preceding Au runs in that during most of it a 12:6:2 merge was employed in the AGS instead of an 8:4:2 merge. This was done to provide higher bunch intensities for RHIC. Since the approach to providing higher bunch intensities is, and has been, to merge more Booster bunches of the same intensity into one final bunch, detailing the longitudinal aspects of this setup seems quite relevant. So, aside from providing an overview of the Au portion of Run 16, this note also contains a series of emittance measurements in the Booster and AGS. Comparisons of these to similar measurements in previous runs are also made in hopes of gaining a better understanding of what factors contribute to the emittance of a bunch at AGS extraction. The note also tries to provide some context in which to understand the various merge schemes and describes a potential 8 to 1 type merge.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

AGS vertical beta function measurements for Run 15

One key parameter for running the AGS efficiently is by maintaining a low emittance. To measure emittance, one needs to measure the beta function throughout the cycle. This can be done by measuring the beta function at the ionization profile monitors (IPM) in the AGS. This tech note delves into the motivation, the measurement, and some strides that were made throughout Run15.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Double and triple-harmonic RF buckets and their use for bunch squeezing in AGS

For the past several years we have merged bunches in AGS in order to achieve the desired intensity per bunch prior to injection into RHIC. The merging is done on a flat porch at or above AGS injection energy. Because the merges involve the reduction of the RF harmonic number by a factor of 2 (for a 2 to 1 merge) and then a factor of 3 (for a 3 to 1 merge), one requires RF frequencies 6hf s , 3hf s , 2hf s and hf s , where f s is the revolution frequency on the porch and h = 4 is the fundamental harmonic number. The standard AGS RF cavities cannot operate at the lowest frequencies 2hf s and hf s ; these are provided by two modified cavities. Upon completion of the merges, the bunches are sitting in harmonic h buckets. In order to be accelerated they need to be squeezed into harmonic 3h buckets. This is accomplished by producing a double-harmonic bucket in which harmonics h and 2h act in concert, and then a triple-harmonic bucket in which harmonics h, 2h, and 3h act in concert. Simulations have shown that the squeeze presents an acceptance bottleneck which limits the longitudinal emittance that can be put into the harmonic 3h bucket. In this note the areas of the double and triple-harmonic buckets are calculated explicitly, and it is shown that these go through a minimum as the RF voltages are raised to the desired values. Several RF voltage ranges are examined, and the acceptance bottleneck is determined for each of these. Finally, the acceptance bottleneck for Au77+ bunches in AGS is calculated for several RF voltage ranges. The main result is that the RF voltages for the low-frequency harmonic h and 2h cavities both must be at least 22 kV in order to achieve an acceptance of 0:6 eV s per nucleon. If the harmonic h and 2h voltages are 15 and 22 kV, respectively, then the acceptance is reduced to 0:548 eV s per nucleon.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Comparing the effect on the AGS longitudinal emittance of gold ions from the BtA stripping foil with and without a Booster Bunch Merge

The aim of this note to better understand the effect of merging the Gold bunches in the Booster into one on the resulting AGS longitudinal emittance as compared to not merging them. The reason it matters whether they are merged or not is because they pass through a stripping foil in the BtA line. Data was taken last run (Run 17) for the case where the bunches are not merged, and it will be compared with data from cases where the bunches are merged. Previous data from Tandem operation will also be considered. There are two main pieces to this puzzle. The first is the ε growth associated with the energy spread due to ‘energy straggling’ in the BtA stripping foil and the second is the effective ε growth associated with the energy loss that occurs while passing through the foil. Both of these effects depend on whether or not the Booster bunches have been merged into one.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Compact, Achromatic Non-scaling FFAG Accelerator for HEP, Commercial and Medical Applications (CRADA FRA-2008-0005 Final Report)

Proton and light-ion accelerators have many research and medical applications, but the current state of technology in accelerators severely limits their widespread use: (1) synchrotrons have an intrinsic low duty cycle and become quite large for light ions; and (2) cyclotrons do not have energy variability and require complex superconducting magnets for high energy. A new concept in non-scaling Fixed-Field Alternating-Gradient (FFAGs) has been invented that incorporates both the energy variability of the synchrotron and the high duty cycle of the cyclotron. The concept uses normal-conducting, combined-function magnets that apply only constant (dipole) and linear-gradient (quadrupole) fields to stabilize the accelerator. This project will develop an optimized design for a new non-scaling and cost-effective innovation in FFAG accelerators. The accelerator design will have optics that can stably accelerate protons to 250 MeV (or higher) and carbon ions to =200 MeV, an energy considered ideal for radiation therapy. Phase I will optimize, fully simulate, and demonstrate the feasibility of this accelerator. Commercial Applications and other Benefits as described by the awardee: The fixed-field acceleration concept should eliminate some of the most pronounced technical difficulties, expense, maintenance, and required expertise faced in conventional proton and light-ion accelerators. In addition to the application for high energy physics, these accelerators should have application in cancer treatment, radiopharmaceuticals, and medical isotope production, and materials science.

43 PARTICLE ACCELERATORS↗