KEK, Ibaraki
KEK is studying the design of the superconducting final focus quadrupoles for the Super KEKB. The system consists of quadrupole-doublet cooled at 1.9 K. The vertical focusing quadrupole has the maximum magnetic field more than 8 T in the superconducting coils. The field gradient at the magnet center is more than 80 T/m and the effective magnetic length is 0.25 m. The horizontal focusing quadrupole is designed with the field gradient of 9.5 T/m and the effective magnetic length of 1.0 m. These magnet parameters will be iterated in the process of optimizing the beam optics. In this paper, the conceptual design of final focusing system and magnets will be reported.
Fermilab, Batavia
Muons, Inc, Batavia
Funding: Supported in part by USDOE STTR Grant DE-FG02-06ER86282
Magnets for the proposed muon cooling demonstration experiment MANX (Muon collider And Neutrino factory eXperiment) have to generate longitudinal solenoid and transverse helical dipole and helical quadrupole fields. This paper discusses the 0.4 M diameter 4-coil Helical Solenoid (HS) model design, manufacturing, and testing that has been done to verify the design concept, fabrication technology, and the magnet system performance. The model quench performance in the FNAL Vertical Magnet Test Facility (VMTF) will be discussed.
Fermilab, Batavia
Muons, Inc, Batavia
Funding: Supported in part by USDOE STTR Grant DE-FG02-07ER84825
This paper presents the results of design studies of a high field section of a helical cooling channel proposed for the 6D muon beam cooling. The results include the magnet aperture limitations, the tunability of field components, the field correction, the superconductor choice and the magnet operation margin.
Fermilab, Batavia
Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359
An R&D proton linac is under construction at FNAL and it will use solenoid lenses in the beam transport line. Because the needed focusing field is on the level of 6 Tesla, superconducting systems are used. In the low energy part of the linac, which uses room temperature accelerating structures, the lenses are placed in stand-alone cryostats. Production of the lenses and cryostats for the low energy section is under way. In the superconducting accelerating sections, the lenses are mounted inside RF cryomodules. Although focusing solenoids for the high energy sections have been designed and prototypes tested, R&D is still ongoing to address magnetic shielding and alignment issues. This report summarizes the performance of lenses for the low-energy part of the linac and presents the status of ongoing R&D.
Fermilab, Batavia
Muons, Inc, Batavia
Funding: Supported in part by USDOE STTR Grant DE-FG02-07ER84825 and by FRA under DOE Contract DE-AC02-07CH11359
The helical cooling channel is proposed to make a quick muon beam phase space cooling in a short channel length. The challenging part of the helical cooling channel magnet design is how to integrate the RF cavity into the compact helical cooling magnet. This report shows the possibility of the integration of the system.
LBNL, Berkeley, California
Third generation Electron Cyclotron Resonance (ECR) ion sources operate at rf frequencies between 20 and 30 GHz and employ NbTi superconducting magnets with a conductor peak field of 6-7 T. A significant gain in performance can be achieved by replacing NbTi with Nb3Sn, allowing solenoids and sextupole coils to reach a field of 15 T in the windings. In this paper we describe the design of a Nb3Sn superconducting magnet for a fourth generation ECR source operating at a rf frequency of 56 GHz. The magnet design features a configuration with an internal sextupole magnet surrounded by three solenoids. A finite element magnetic model has been used to investigate conductor peak fields and the operational margins. Results of the numerical analysis are presented and discussed.
LBNL, Berkeley, California
ICST, Harbin
UMiss, University, Mississippi
Funding: This work is supported by funds under the “985-2” plan of HIT. This work is also supported by the Office of Science, US-DOE under DOE contract DE-AC02-05CH11231 and by NSF through NSF-MRI-0722656.
The superconducting coupling solenoid for MuCOOL and MICE will have an inside radius of 750 mm, and a coil length of 285 mm. The MuCOOL coupling coil is identical to the MICE coupling coils. The MICE coupling magnet will have a self inductance of 592 H. When operated at it maximum design current of 210 A (the highest momentum operation of MICE), the magnet stored energy will be about 13 MJ. These magnets will be kept cold using a pair of pulse tube cryocoolers that deliver 1.5 W at 4.2 K and 55 W at 60 K. This report describes the progress on the MuCOOL and MICE coupling magnet design and engineering. The progress on the construction of the first coupling coil will also be presented.
LBNL, Berkeley, California
Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231.
The Muon Ionization Cooling Experiment (MICE) is an international collaboration that will demonstrate ionization cooling in a section of a realistic cooling channel using a muon beam at Rutherford Appleton Laboratory (RAL) in the UK. At each end of the cooling channel a spectrometer solenoid magnet consisting of five superconducting coils will provide a 4 tesla uniform field region. The scintillating fiber tracker within the magnet bore tubes will measure the emittance of the muon beam as it enters and exits the cooling channel. The 400 mm diameter warm bore, 3 meter long magnets incorporate a cold mass consisting of two coil sections wound on a single aluminum mandrel: a three-coil spectrometer magnet and a two-coil section that matches the solenoid uniform field into the MICE cooling channel. The fabrication of the spectrometer solenoids has been completed, and preliminary testing and field mapping of the magnets is nearly complete. The key design features of the spectrometer solenoid magnets are presented along with a summary of the progress on the testing and magnetic measurements.
Muons, Inc, Batavia
NHMFL, Tallahassee, Florida
High temperature superconductors (HTS) have been shown to carry significant current density in the presence of extremely high magnetic fields when operated at low temperature. The successful design of magnets needed for high energy physics applications using such high field superconductor depends critically on the detailed wire or conductor parameters which are still under development and not yet well-defined. The HTS is being developed for accelerator use by concentrating on the design of solenoid magnet that will have a useful role in cooling muon beam phase space. A conceptual design of a high field solenoid using YBCO conductor is being analyzed. Mechanical properties of the HTS conductors will be measured along with engineering current densities (JE) as a function of temperature and strain to extend the HTS specifications to conditions needed for low temperature applications. HTS quench properties are proposed to be measured and quench protection schemes developed for the solenoid magnet.
Sigmaphi, Vannes
Vector Fields Ltd., Oxford
Oxford Instruments, Accelerator Technology Group, Oxford, Oxon
A tender for the study and construction of a large superconducting split solenoid for the C400 carbon therapy cyclotron was issued by IBA in March 2008 and awarded to Sigamphi. Although the current density is moderate, the large radius and average field imply quite a high level of hoop stress. Simple formulas range between 140 and 180 MPa and, with such large values and uncertainties, it was felt necessary to perform a finite element analysis of the structure. Average fields in a cyclotron are very well modeled using an axially symmetrical structure and the stress was therefore studied using the stress module of the Vector Fields Opera2d suite. Different models were tried with different levels of details. A comparison is made between them as well as with the analytical results.
BNL, Upton, Long Island, New York
The low energy (35 keV) and medium energy (750 keV) transport lines for (un)polarized H- have been reconfigured to reduce beam losses and the beam emittance out of the 200 MeV Linac. The medium energy line in the original layout was 7 m long, and had ten quadrupoles, two beam choppers, and three bunchers. The bunchers were necessary to keep the beam bunched at the entrance of the Linac. About 35% beam loss occurred, and the emittance growth was several fold. In the new layout, the 750 keV line is only 0.7 m long, with three quads and one buncher. To preserve beam polarization in the 35 keV line, the solenoid in front of the RFQ (35 keV to 750 keV) was replaced with an Einzel lens. To reduce the spin-precession in the LEBT, which may cause the depolarization, a 47.4 degree bend was removed and focusing solenoid in front of RFQ was replaced with an Einzel lens. We will present the experimental result of the upgrade.
Muons, Inc, Batavia
UMD, College Park, Maryland
ORNL, Oak Ridge, Tennessee
Funding: Supported in part by the US DOE Contract DE-AC05-00OR22725
Spallation neutron source user facilities require reliable, intense beams of protons. The technique of H- charge exchange injection into a storage ring or synchrotron can provide the needed beam currents, but may be limited by the ion sources that have currents and reliability that do not meet future requirements and emittances that are too large for efficient acceleration. In this project we are developing an H- source which will synthesize the most important developments in the field of negative ion sources to provide high current, small emittance, good lifetime, high reliability, and power efficiency. We describe planned modifications to the present external antenna source at SNS that involve: 1) replacing the present 2 MHz plasma-forming solenoid antenna with a 60 MHz saddle-type antenna and 2) replacing the permanent multicusp magnet with a weaker electro-magnet, in order to increase the plasma density near the outlet aperture. The SNS test stand will then be used to verify simulations of this approach that indicate significant improvements in H- output current and efficiency, where lower RF power will allow higher duty factor, longer source lifetime, and/or better reliability.
Diamond, Oxfordshire
To investigate ultrafast dynamics of physical or chemical systems, ultrashort X-rays or electron beams may be used. Compared to X-rays, electron beams are less destructive to material and the scattering cross section is larger, however it is difficult to decrease the electron beam pulse length due to space charge forces. One way of overcoming this difficulty is by means of a photocathode RF gun, which allows the beam energy to be rapidly increased immediately after the electron emission from the photocathode, minimizing therefore the pulse lengthening due to space charge forces. For time-resolved observation of atomic processes electron beams shorter than 100 fs (fwhm) with small divergence are required. In this paper, a conceptual design of a gun system is proposed with beam parameters optimized for relativistic electron diffraction experiments.
KEK, Ibaraki
The first operation of the positron production with a tungsten single-crystal target has been performed at the positron source of the KEKB injector linac for the KEK B-factory (KEKB) from September 2006 to June 2007 (~10 months). Previously we carried out the systematic studies on the positron-production efficiencies with tungsten crystals having various thickness using 4- and 8-GeV electron beams at the test beam line during the term of 2000-2005. Finally, we optimized the thickness of the tungsten crystal at 4 GeV and developed both the target fabrication technique and the crystal-axis alignment technique in 2006. After the systematic studies, we installed a tungsten crystal target at the KEKB positron source without any significant modifications for the positron source. The data on the positron production, especially, the positron-production efficiencies and stabilities in terms of the primary electron and positron beams, were obtained during the nominal KEKB operation in this term. We summarize the long-term operational performance on the positron production with the tungsten crystal target at the KEKB injector linac in this report.
INFN/LNF, Frascati (Roma)
UCLA, Los Angeles, California
Istituto Nazionale di Fisica Nucleare, Milano
INFN-Roma II, Roma
ENEA C.R. Frascati, Frascati (Roma)
University of Tehran, Tehran
INFN-Roma, Roma
One of the main goals of the SPARC high brightness photoinjector is the experimental demonstration of the emittance compensation process while compressing the beam with the velocity bunching technique, also named RF compressor. For this reason, the first two S-band travelling wave accelerating structures downstream of the RF gun are embedded in a long solenoid, in order to control the space charge induced emittace oscillations during the compression process. An RF deflecting cavity placed at the exit of the third accelerating structure allows bunch length measurements with a resolution of 50 μm. During the current SPARC run a parametric experimental study of the velocity bunching technique has been performed. The beam bunch length and projected emittance have been measured at 120 MeV as a function of the injection phase in the first linac, and for different solenoid field values. In this paper we describe the experimental layout and the results obtained thus far. Comparisons with simulations are also reported.
Muons, Inc, Batavia
Fermilab, Batavia
The study of rare processes using a beam of muons that stop in a target provides access to new physics at and beyond the reach of energy frontier colliders. The flux of stopping muons is limited by the pion production process and by stochastic processes in the material used to slow down the decay muons. Innovative muon beam collection and cooling techniques are applied to the design of stopping muon beams in order to provide better beams for such experiments. Such intense stopping beams will also support the development of applications such as muon spin resonance and muon-catalyzed fusion.
NSRRC, Hsinchu
NTHU, Hsinchu
A high brightness photo-injector for light source research applications is being built at NSRRC. This injector consists of a laser driven RF gun with an emittance compensation solenoid and linac sections that booster the beam energy up to 150 MeV. A 266 nm pico-second UV laser system which generates a 300 uJ laser pulse with pulse which can be varied by a UV stretcher from1 to15 ps have been installed and laser shaping techniques will be developed to reduce the emittance growth. The RF gun is a 1.6 cell cavity operating at pi mode and the solenoid used to compensate the emittance growth due to the space charge effect will be set up in the spring of 2009. Beam dynamics study is performed by PARMELA and simulation results show that a normalized rms transverse emittance of 0.7 mm-mrad with a 10 ps flattop pulse at 1 nC charge can be achieved. Measurements of characteristics of the RF gun and the solenoid will be presented.
USTC/NSRL, Hefei, Anhui
A photocathode injector system is developing at NSRL. A BNL type S-band photocathode RF gun has been built. The emittance will be compensated by a Solenoid. The driving laser is a high-Q product. It will be reformed into uniform distribution in the transverse distribution, but will not in the longitudinal direction. The whole system will be tested soon.
LBNL, Berkeley, California
Funding: This work was supported by the Office of Science, U. S. Department of Energy, under Contract No. DE-AC02-05CH11231.
There is considerable interest in the use of muon beams to create either an intense source of decay neutrinos aimed at a detector located 3000-7500 km away (a Neutrino Factory), or a Muon Collider that produces high-luminosity collisions at the energy frontier. R&D aimed at producing these facilities has been under way for more than 10 years. This paper will review experimental results from MuCool, MERIT, and MICE and indicate the extent to which they will provide proof-of-principle demonstrations of the key technologies required for a Neutrino Factory or Muon Collider. Progress in constructing components for the MICE experiment will be described.
BNL, Upton, Long Island, New York
In the past few years, there have been a number of advances in the design and supporting R&D for a machine to cool, accelerate and collide TeV muon beams. This talk will review progress and discuss how such a machine might evolve from programs to build high intensity proton sources and neutrino factories.
Fermilab, Batavia
Muons, Inc, Batavia
We have developed a new method for capture, bunching and phase-energy rotation of secondary beams from a proton source, using high-frequency rf systems. The method is the baseline for muon capture in the International scoping study for a neutrino factory. In this method, a proton bunch on a target creates secondaries that drift into a capture transport channel. A sequence of rf cavities forms the resulting muon beams into strings of bunches of differing energies, aligns the bunches to (nearly) equal central energies, and initiates ionization cooling. For the International Design Study the method must be optimized for performance and cost, and variations will be explored. In this paper we present results of optimization and variation studies toward obtaining the maximum number of muons for a neutrino factory, as well as for a future muon collider.
Fermilab, Batavia
Funding: Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Ionization cooling is essential for realization of Muon Collider, muons beam based neutrino factories and other experiments involving muons. The simplest structure - absorber(s) immersed in alternating solenoidal magnetic field - provides only transverse cooling since the longitudinal motion in the most suitable momentum range (2-300MeV/c) is naturally antidamped. To overcome this difficulty it is proposed to periodically tilt solenoids so that a rotating transverse magnetic field was created. By choosing the phase advance per period above a multiple of 2pi it is possible to ensure that muons with higher momentum make a longer path in the absorber (whether distributed or localized) thus providing longitudinal damping. Basic theory of such channel and results of tracking simulations are presented.
PU, Princeton, New Jersey
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL, Chilton, Didcot, Oxon
ORNL, Oak Ridge, Tennessee
CERN, Geneva
BNL, Upton, Long Island, New York
Fermilab, Batavia
The MERIT (MERcury Intense Target) experiment was run in the fall of 2007 using 14 and 24 GeV intense proton beams from the CERN PS. It is a proof-of-principle experiment designed to validate a target concept for producing an intense muon source for a future muon collider or neutrino factory. The experiment successfully demonstrated a target technique for multi-MW proton beams that utilizes a free-flowing liquid metal jet within the confines of a high-field solenoid. We describe the experimental strategy and parameters, as well as the results obtained and their implications for future muon-based accelerator facilities.
Muons, Inc, Batavia
Fermilab, Batavia
Funding: Supported by STTR Grant DE-FG02-07ER86320 and FRA DOE contract number DE-AC02-07CH11359
Originally conceived as a solution for FFAG applications, a new compact RF cavity design that tunes rapidly over various frequency ranges can be used to upgrade existing machines. The design being developed uses orthogonally biased garnet cores for fast frequency tuning and liquid dielectric to adjust the frequency range and to control the core temperature. We describe measurements of candidate ferrite and dielectric materials. The first use of the new cavity concept will be for improvements to the 8 GeV Fermilab Booster synchrotron.
Muons, Inc, Batavia
Fermilab, Batavia
Funding: Supported in part by USDOE Contract. DE-AC05-84-ER-40150 and by FRA DOE contract number DE-AC02-07CH11359
Magnetrons are low-cost highly-efficient microwave sources, but they have several limitations, primarily centered about the phase and frequency stability of their output. When the stability requirements are low, such as for medical accelerators or kitchen ovens, magnetrons are the very efficient power source of choice. But for high energy accelerators, because of the need for frequency and phase stability–-proton accelerators need 1-2 degrees source phase stability, and electron accelerators need .1-.2 degrees of phase stability–-they have rarely been used. We describe a novel variable frequency cavity technique which will be utilized to phase and frequency lock magnetrons.
IIT, Chicago, Illinois
Fermilab, Batavia
LBNL, Berkeley, California
ANL, Argonne
Funding: The United States Department of Energy
The accelerating gradient in a RF cavity is limited by many factors such as the surface material properties, RF frequency, the external magnetic field and the gas pressure inside the cavity. In the MuCool Program, RF cavities are studied with the aim of understanding these basic mechanisms and improving their maximum stable accelerating gradient. These cavities are being developed for muon ionization cooling channel for a Neutrino Factory or Muon Collider. We report studies using the 805 MHz and 201 MHz RF cavities in the MuCool Test Area (MTA) at Fermilab. New results include data from buttons of different materials mounted in the 805 MHz cavity, study of the accelerating gradient in the 201 MHz cavity and X-ray background radiation from the cavities due to Bremsstrahlung. The 201 MHz cavity has been shown to be stable at 19 MV/m at zero magnetic field, well in excess of its 16 MV/m design gradient. We will also discuss results from the 201 MHz cavity study in magnetic field and introduce the test of E × B effects with the 805 MHz box cavity.
USTC/NSRL, Hefei, Anhui
In china, polymer radiation processing has become one of the most important processing industries. Electron beam accelerator or radioactive source is usually used as radiation processing source. For radiation crosslinking application, physical design, construction and testing of a electron beam facility is introduced because of it’s much higher dose rate and efficiency. Main part of this facility is a 10MeV traveling wave electron linac with constant impedance accelerating structure. It is the first electron beam facility designed for polymer radiation processing by National Synchrotron Radiation Laboratory (NSRL) in China. In the paper, a start to end simulation is finished to optimize electron beam dynamics in the linac. Measurement results of some subassemblies are presented. The linac construction has been finished just now. Testing experiments prove that the facility can work well for radiation crosslinking application.
BNL, Upton, Long Island, New York
Ultrafast electron diffraction (UED) is a promising technique that allows us to observe a molecular structure transition on a time scale on the order of femtoseconds. The UED has several advantages over the competing technology, X-Ray Free Electron Laser (XFEL) in terms of its compactness, 6 orders of magnitude larger cross section, and less damaging ability to the samples being probed. Present state-of-the-art UED systems utilize subrelativistic electron bunches as the probing beam. With such low energy, however, the number of electrons in the bunch must be significantly decreased for a short bunch length (~100 fs) due to space charge effects. This limits the detection capability of such keV UED devices. To overcome this issue, a UED system using an MeV electron beam has been proposed, and designed at Source Development Laboratory (SDL) in National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL). A detailed performance analysis of this system using the particle tracking code, GPT, from the photoinjector cathode to the detector, will be presented, as well as the status of the commissioning of our UED system.
CERN, Geneva
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL, Chilton, Didcot, Oxon
ORNL, Oak Ridge, Tennessee
BNL, Upton, Long Island, New York
PU, Princeton, New Jersey
Fermilab, Batavia
The MERIT experiment is a proof-of-principle test of a target system for high power proton beam to be used as front-end for a neutrino factory complex or a muon collider. The experiment took data in autumn 2007 with the fast extracted beam from the CERN Proton Synchrotron (PS) to a maximum intensity of about 30·1012 protons per pulse. We report results from the portion of the MERIT experiment in which separated beam pulses were delivered to a free mercury jet target with time intervals between pulses varying from 2 to 700 microseconds. The analysis is based on the responses of particle detectors placed along side and downstream of the target.
LBNL, Berkeley, California
PPPL, Princeton, New Jersey
Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Recent changes to the NDCX beamline offer the promise of higher current compressed bunches, with correspondingly larger fluences, delivered to the target plane for ion-beam driven warm dense matter experiments. We report modeling and commissioning results of the upgraded NDCX beamline that includes a new induction bunching module with approximately twice the volt-seconds and greater tuning flexibility, combined with a longer neutralized drift compression channel.
INFN-Napoli, Napoli
UCR, Riverside, California
Funding: World Wide Collaboration of a large fraction of the international agencies.
Muon ionization cooling provides the only practical solution to prepare high brilliance beams necessary for a neutrino factory or muon colliders. The muon ionization cooling experiment (MICE) is under development at the Rutherford Appleton Laboratory (UK). It comprises a dedicated beam line to generate a range of input emittance and momentum, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. A first measurement of emittance is performed in the upstream magnetic spectrometer with a scintillating fiber tracker. A cooling cell will then follow, alternating energy loss in liquid hydrogen and RF acceleration. A second spectrometer identical to the first one and a particle identification system provide a measurement of the outgoing emittance. By April 2009 it is expected that the beam and first set of detectors will have been commissioned, and a first measurement of input beam emittance may be reported. Along with the plan of measurements of emittance and cooling that will follow in the second half of 2009 and in 2010.
BNL, Upton, Long Island, New York
UMD, College Park, Maryland
JLAB, Newport News, Virginia
Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office
In this paper we report on a proof of principle experiment for demonstrating the possibility of reconstructing the time resolved-phase-space distribution of a space-charge dominated beam by a tomographic technique which provides us with far more information than a time-sliced emittance. We emphasize that this work describes and demonstrates a new methodology which can be applicable to any beam pulse using imaging methods with the appropriate time resolution for the pulse duration. The combination of a high precision tomographic diagnostic with fast imaging screens and a gated camera are used to produce phase space maps of two beams: one with a parabolic current profile and another with a short perturbation atop a rectangular pulse. The correlations between longitudinal and transverse phase spaces are apparent and their impact on the dynamics is discussed.
SLAC, Menlo Park, California
Microbunching instability is one of the most challenging threats to FEL performances. The most effective way to suppress microbunching instability is to increase the relative slice energy spread of the beam. In this paper we show that the velocity bunching inherently mitigates the microbunching instability. PARMELA simulation indicates that the initial current modulations are suppressed in velocity bunching process, which may be attributed to the strong Landau damping from the relatively large relative slice energy spread.
Kyoto IAE, Kyoto
UVSOR, Okazaki
A short period undulator with strong magnetic field will play an important role in future light source. We proposed a new type of staggered array undulator by use of bulk high-Tc superconductor*. We have constructed a prototype of the undulator using DyBaCuO bulk superconductors and a normal conducting solenoid. In the conference, we will present results of the magnetic field measurement and discuss on the feasibility of the new type bulk high-Tc staggered array undulator.
*R. Kinjo et al., Proceedings of the FEL2008, in press.
SLAC, Menlo Park, California
INFN/LNF, Frascati (Roma)
BINP SB RAS, Novosibirsk
The proposed SuperB factory will provide longitudinal polarized electrons to the experiment. Vertically polarized electrons will be injected into the High Energy Ring; the vertical spin orientation will be locally rotated into the longitudinal direction before the interaction point and back afterwards to avoid spin depolarization. The spin rotators can be designed using compensated solenoids–-as proposed by Zholents and Litvinenko–-to rotate the spin into the horizontal plane, followed by dipoles for horizontal spin rotation into the longitudinal direction. Such spin rotators have been matched into the existing lattice and combined with the crab-waist IR. Several ways of achieving this are explored, that differ in the degree of spin matching achieved and the overall geometry of the interaction region. The spin rotation can also be achieved by a series of dipole magnets only, which present a different optical matching problem. We will compare the different scenarios leading up to the adopted solution.
ORNL, Oak Ridge, Tennessee
CERN, Geneva
BNL, Upton, Long Island, New York
PU, Princeton, New Jersey
Funding: U.S. Department of Energy contract DE-AC05-00OR22725
Operation of a mercury jet delivery system is presented. The delivery system is part of the Mercury Intense Target (MERIT) Experiment, a proof-of-principle experiment conducted at CERN in 2007 which demonstrated the feasibility of using an unconstrained jet of mercury as a target for a future Neutrino Factory or Muon Collider. The Hg system was designed to produce a 1-cm-diameter, 20 m/s Hg jet inside a high-field (15 Tesla), 15-cm-bore solenoid magnet. A high-speed optical diagnostic system allowed observation of the interaction of the jet with both 14- and 24-GeV proton beams. Performance of the Hg system during the in-beam experiment will be presented.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
CERN, Geneva
In Muon Ionisation Cooling, closely packed high-field RF cavities are interspersed with energy-absorbing material in order to reduce particle beam emittance. Transverse focussing of the muon beams is achieved by superconducting magnets. This results in the RF cavities sitting in intense magnetic fields. Recent studies have shown that this may limit the peak gradient that can be achieved in the RF cavities. In this paper, we study the effect that a reduced RF gradient may have on the cooling performance of the Neutrino Factory lattice and examine methods to mitigate the effect.
Muons, Inc, Batavia
Fermilab, Batavia
Funding: Supported in part by DOE STTR grant DE-FG02-05ER86252
Earlier studies on the front end of a neutrino factory or muon collider have relied on a single simulation tool, ICOOL. We present here a cross-check against another simulation tool, G4beamline. We also perform a study in economizing the number of RF cavity frequencies and gradients. We conclude with a discussion of future studies.
Fermilab, Batavia
Muons, Inc, Batavia
Funding: Supported in part by USDOE STTR Grant DE-FG02-05ER86252 and FRA DOE contract number DE-AC02-07CH11359
Gas-filled RF cavities can provide high-gradient accelerating fields for muons, and can be used for simultaneous acceleration and cooling of muons. In this paper we explore using these cavities in the front-end of the capture and cooling systems for neutrino factories and muon colliders. We consider using gas-filled RF cavities for the initial front end cooling systems. We also consider using them for simultaneous phase-energy rotation and cooling in a front-end system. We also consider using lower-density RF cavities, where the gas density is primarily for RF breakdown suppression, with less cooling effect. Pressurized RF cavities enable higher gradient rf within magnetic fields than is possible with evacuated cavities, enabling more options in the front-end. The status of designs of the capture, phase rotation, and precooling systems of muon beams in pressurized cavities is described.
Fermilab, Batavia
Muons, Inc, Batavia
Northern Illinois University, DeKalb, Illinois
Funding: Supported in part by USDOE STTR Grant DE-FG02-06ER86282 and by FRA under DOE Contract DE-AC02-07CH11359
MANX is a six-dimensional muon ionization cooling demonstration experiment based on the concept of a helical cooling channel in which a beam of muons loses energy in a continuous helium or hydrogen absorber while passing through a special superconducting magnet called a helical solenoid. The goals of the experiment include tests of the theory of the helical cooling channel and the helical solenoid implementation of it, verification of the simulation programs, and a demonstration of effective six-dimensional cooling of a muon beam. We report the status of the experiment and in particular, the proposal to have MANX follow MICE at the Rutherford-Appleton Laboratory (RAL) as an extension of the MICE experimental program. We describe the economies of such an approach which allow the MICE beam line and much of the MICE apparatus and expertise to be reused.
Muons, Inc, Batavia
Fermilab, Batavia
Funding: Supported in part by USDOE STTR Grant DE-FG02-06ER86282
The MANX experiment is to demonstrate the reduction of 6D muon phase space emittance using a continuous liquid absorber to provide ionization cooling in a helical solenoid magnetic channel. The experiment involves the construction of a short two-period long helical cooling channel (HCC) to reduce the muon invariant emittance by a factor of two. The HCC would replace the current cooling section of the MICE experiment now being setup at the Rutherford Appleton Laboratory. The MANX experiment would use the existing MICE spectrometers and muon beam line. This paper shall consider the various approaches to integrate MANX into the RAL hall using the MICE spectrometers. This study shall discuss the matching schemes used to minimize losses and prevent emittance growth between the MICE spectrometers and the MANX HCC. Also the placement of additional detection planes in the matching region and the HCC to improve the resolution will be examined.
Muons, Inc, Batavia
Illinois Institute of Technology, Chicago, Illinois
Funding: Work supported in part by USDOE STTR Grant DE FG02 08ER86281.
We describe an approach that can extend the utility of frictional cooling, originally developed for muon beams, to other particles and ions, producing beams of exceptionally low normalized emittance. Moreover, via this approach the small momentum acceptance typical of frictional cooling channels can be increased by two to three orders of magnitude, making it possible to handle much larger intensities with much higher transmission, while preserving the exceptionally low normalized emittance of the output. Simulation studies have been used to optimize the design and performance for a variety of ions and particles, and an inexpensive experiment has been designed to test and verify the concept and simulations, using alpha particles from a radioactive source.
UCLA, Los Angeles, California
We describe the Li Lens concept for a cooler for the transverse emittance for a μ+μ- collider. Different configurations are discussed such as Linear Cooler, Ring Coolers all with Li Lens inserts. We then describe a program to study the construction of Liquid Li Lens and a possible experiment at FNAL.
UCLA, Los Angeles, California
BNL, Upton, Long Island, New York
Funding: DOE
A study of target parameters for a high-intensity, liquid mercury jet target system for a neutrino factory or muon collider is presented. Using the MARS code, we simulate particle production initiated by incoming protons with kinetic energies between 2 and 100 GeV. For each proton beam energy, we optimize the geometric parameters of the target: the mercury jet radius, the incoming proton beam angle, and the crossing angle between the mercury jet and the proton beam. The number of muons surviving through an ionization cooling channel is determined as a function of the proton beam energy
Sokendai, Ibaraki
KEK, Ibaraki
Toyobo Research Institute, Shiga
Main cause of premature quench in superconducting magnet is the heat generated due to sudden superconducting wire motion. The wire motion occurs where electromagnetic force to conductors exceeds frictional force on surfaces of the conductors. Hence, frictional properties of the conductors and winding structures are important parameters for characterizing stability of the superconducting windings. Experiments were carried out to detect the superconducting wire motion under the influence of varying electromagnetic force. The wire movement is detected by observing the spike in voltage of the superconducting sample wire. From the time profile of voltage spike, distance moved by superconducting wire is estimated. Insulating material such as Dyneema random sheet, Dyneema non-woven sheet and Dyneema fiber cloth were used at the interface of superconducting wire and base material. Dyneema has low frictional coefficient and negative thermal expansion. The experimental findings will be discussed.
BNL, Upton, Long Island, New York
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL, Chilton, Didcot, Oxon
ORNL, Oak Ridge, Tennessee
CERN, Geneva
PU, Princeton, New Jersey
Fermilab, Batavia
We report on the analysis of data collected from the optical diagnostics of the MERIT experiment which was run at CERN in the fall of 2007. The breakup of the free mercury jet resulting from the impact of intense proton beams from the CERN PS within a magnetic field environment is described.
STFC/RAL, Chilton, Didcot, Oxon
Exeter University, Exeter, Devon
Gericke LTD, Ashton-under-Lyne
This paper proposes a technology based on fluidized powder which could be employed as a high power target (and beam dump), for example in a future Neutrino Factory or Muon Collider. A fluidized powder target is believed to bring together some advantages of both the solid and liquid phase whilst avoiding some of their drawbacks. The current Neutrino Factory and Muon Collider proposals require the use of a high Z target material withstanding beam ionisation heating of around 1 MW. The article proposes to use a dense tungsten powder jet as an alternative to the baseline open mercury jet for interaction with the proton beam inside the high field capture solenoid. The preliminary experimental results on the production and on the characteristics of a dense horizontal tungsten powder jet are presented. The morphology of the jet is analysed and presented as a function of the driving parameters (e.g. pneumatic supply pressure, boundary conditions of the jet, etc.). A test rig was developed to investigate the reliability of lean and dense phase pneumatic conveying of tungsten powder and the results of such experiments are discussed in the paper.
LANL, Los Alamos, New Mexico
LLNL, Livermore, California
NSTec, Los Alamos, New Mexico
Voss Scientific, Albuquerque, New Mexico
SAIC, Los Alamos, New Mexico
Funding: This work was supported by the US National Nuclear Security Agency and the US Department of Energy under contract W-7405-ENG-36.
The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 microsecond, which can be scraped off in a beam-head cleanup zone (BCUZ) before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and we will present data for the resulting beam transport and dynamics. We will also present beam stability data, and relate these to previous stability experiments at lower current and energy*.
* “Long-pulse beam stability experiments on the DARHT-II linear induction accelerator,” Carl Ekdahl, et al., IEEE Trans. Plasma. Sci. Vol. 34, 2006, pp. 460-466
LBNL, Berkeley, California
LLNL, Livermore, California
PPPL, Princeton, New Jersey
Voss Scientific, Albuquerque, New Mexico
The Heavy-Ion Fusion Sciences Virtual National Laboratory is pursuing an approach to target heating experiments in the warm dense matter regime, using space-charge-dominated ion beams that are simultaneously longitudinally bunched and transversely focused. Longitudinal beam compression by large factors has been demonstrated in the Neutralized Drift Compression Experiment (NDCX) with controlled ramps and forced neutralization. Using an injected 30 mA K+ ion beam with initial kinetic energy 0.3 MeV, axial compression leading to ~100X current amplification and simultaneous radial focusing to a few mm have led to encouraging energy deposition approaching the intensities required for eV-range target heating experiments. We discuss the status of several improvements to NDCX to reach the necessary higher beam intensities, including:
- greater axial compression via a longer velocity ramp;
- beam steering dipoles to mitigate aberrations in the bunching module;
- time-dependent focusing elements to correct considerable chromatic aberrations; and
- plasma injection improvements to establish a plasma density always greater than the beam density, expected to be >1013 cm-3.
CEA, Gif-sur-Yvette
INFN/LNL, Legnaro (PD)
During the EVEDA (Engineering Validation and Engineering Design Activities) phase of the IFMIF (International Fusion Materials Irradiation Facility) project, a 125 mA/9 MeV accelerator prototype will be built, tested and operated in Rokkasho-Mura (Japan). The injector section of this accelerator is composed by an ECR source, delivering a 140 mA deuteron beam at 100 keV, and a low energy beam transport (LEBT) line required to match the beam for the RFQ injection. The proposed design for the LEBT is based on a dual solenoids focusing scheme. In order to takes into account the space charge compensation of the beam induced by the ionisation of the residual gas, a 3D particle-in-cell code (SOLMAXP) has been developed for the beam dynamics calculations. The LEBT parameters have been optimized in order to maximize the beam transmission through the RFQ. The final LEBT design, as well as the simulation results, are presented.
CEA, Gif-sur-Yvette
The 250 mA, 40 MeV cw deuteron beam required for the International Fusion Materials Irradiation Facility (IFMIF) will be provided by two 125 mA linacs. In order to accelerate the beam from 5 MeV to 40 MeV, a superconducting linac, housed in four cryomodules, is proposed. The design is based on two beta families (beta=0.094 and beta=0.166) of half-wave resonators (HWR) at 175 MHz. The transverse focusing is achieved using one solenoid coil per lattice. This paper presents the extensive multi-particle beam dynamics simulations that have been performed to adapt the beam along the SC-HWR structure in such a high space charge regime. As one of the constraints of the IFMIF linac is hands-on maintenance, specific optimizations have been done to minimize the beam occupancy in the line (halo). A Monte Carlo error analysis has also been carried out to study the effects of misalignments or field imperfections.
Fermilab, Batavia
Funding: Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Existing codes for accelerator design (e.g. MAD) are not well suited for ionization cooling channels where particles exhibit strongly dissipative and nonlinear motion. A system of Mathematica programs was developed which allows to: 1) find periodic orbit and eigenvectors of the transfer matrix around it with account of (regular part of) ionization losses and feeddown effect from nonlinear fields; 2) compute emittance growth due to scattering and straggling, find equilibrium values (if exist); 3) analyze nonlinear effects such as dependence of tunes and damping rates on the amplitudes, resonance excitation; 4) perform tracking with account of stochastic processes. Underlying theory and application to helical cooling channel are presented.
INFN/LNF, Frascati (Roma)
High gain free electron lasers require the production of a high brightness electron beam that is a low emittance, high current beam. To this aim the injector and linac design and theirs operation are the leading edge. The successful operation of the SCSS FEL driven by a C-band linac has demonstrated that C-band is a mature technology and it is very attractive in terms of gradient and compactness. In this paper it is described a beam dynamics study, made with the Homdyn code, for a C-band linac driven FEL with S-band photo-injector. The key point is to match the longitudinal phase space of the S-band photo-injector with the C-band linac using the velocity bunching technique. The result is a brightness up to 1015A/m2, obtained with a low emittance and a relaxed peak current.
LLNL, Livermore, California
LBNL, Berkeley, California
Funding: Work performed under the auspices of US Department of Energy by LLNL under Contract DE- AC52-07NA27344 and by LBNL under Contract DE-AC03-76SF00098.
The Virtual National Laboratory for Heavy-Ion Fusion is developing a physics design for NDCX-II, an experiment to study warm dense matter heated by ions near the Bragg-peak energy. Present plans call for using about thirty induction cells to accelerate 30 nC of Li+ ions to more than 3 MeV, followed by neutralized drift-compression. To heat targets to useful temperatures, the beam must be compressed to a sub-millimeter radius and a duration of about 1 ns. An interactive 1-D particle-in-cell simulation with an electrostatic field solver, acceleation-gap fringe fields, and a library of realizable analytic waveforms has been used for developing NDCX-II acceleration schedules. Multidimensional source-to-final-focus simulations with the particle-in-cell code Warp have validated this 1-D model and have been used both to design transverse focusing and to compensate for injection non-uniformities and 3-D effects. Results from this work are presented, and ongoing work to replace the analytic waveforms with output from circuit models is discussed.
Muons, Inc, Batavia
Funding: Supported in part by USDOE Contract DE-FG02-6ER86281.
The G4beamline program is based on the well-established Geant4 toolkit used to simulate the interactions of particles and photons with matter. Until now, only a single particle at a time could be tracked and there are no interactions between particles. Recent designs for high pressure RF cavities and other novel devices achieving extreme muon cooling require that the effect of space charge be included in the simulations. A new tracking manager in G4beamline propagates a number of particles (typically 1,000-10,000) in parallel, stepping all particles in time. This allows all of the usual Geant4 physics interactions to be applied, plus collective computations. A simple macroparticle-based model is used to represent ~108 charges with an ellipsoidal charge density. At intervals the appropriate macroparticle size and shape are recalculated, the electric and magnetic fields are determined, and an impulse is applied to the simulated particles. Comparisons to standard space charge codes are presented.
ANL, Argonne
Northern Illinois University, DeKalb, Illinois
Funding: The work is supported by the U.S. Department of Energy under Contract No. DE-AC02-06CH11357 with Argonne National Laboratory.
Phase space measurements of RF photoinjectors have usually been done with multislit masks or scanning slits. These systems implicitly ignore the correlations between the X and Y planes and thus yield measurements of the projected 2D phase space distributions. In contrast, a grid-patterned pepper-pot is capable of measuring the full 4D transverse phase space distribution, f(x,x',y,y'). 4D measurements allow precise tuning of electron beams with large canonical angular momentum, important for electron cooling and flat beam transformation, as well as zeroing the magnetic field on the photocathode is zero for ultra low emittance applications (e.g. SASE FEL, ERL FEL). In this talk, we report on a parametric set of measurements to characterize the 4D transverse phase space of the 1 nC electron beam from the Argonne Wakefield Accelerator (AWA) RF photoinjector. The diagnostic is simulated with TStep, including the passage of the electron beam trough the mask and tracking of the beamlets to the imaging screen. The phase space retrieval algorithm is then bench marked against simulations and measurements.
DPNC, Genève
The MICE experiment aims at demonstrating that the performances of the muon ionization technique are compatible with the requirements of the neutrino factory and the muon collider. The experiment is running at the Rutherford-Appleton Laboratory in the UK using the ISIS proton beam on a dynamic target as a muon source. Brand new target system and muon beam line have been designed, built and installed during the last two years. On the other hand, particle identification detectors needed for the experiment have also been installed and commissioned. This presentation describes how we made use of Time of Flight detectors, aerogel Cherenkov counters and electro-magnetic calorimeter sensors to characterize the content of the MICE beam between 100 and 480 MeV/c.
IUCF, Bloomington, Indiana
Fermilab, Batavia
The proton ion source for the High Intensity Neutrino Source (HINS) Linac front-end at Fermilab has been successfully commissioned. It produces a 50 keV, 3 msec beam pulse with a peak current greater than 20 mA at 2.5 Hz. The beam is transported to the radio-frequency quadrupole (RFQ) by a low energy beam transport (LEBT) that consists of two focusing solenoids, four steering dipole magnets and a beam current transformer. To understand beam transmission through the RFQ, it is important to characterize the 50 keV beam before connecting the LEBT to the RFQ. A wire scanner and a Faraday cup are temporarily installed at the exit of the LEBT to study the beam parameters. Beam profile measurements are made for different LEBT settings and results are compared to those from computer simulations. In lieu of direct emittance measurements, a solenoid variation method based on profile measurements is used to reconstruct the beam emittance.
Ankara University, Faculty of Engineering, Tandogan, Ankara
FZD, Dresden
SDU, Isparta
Funding: State Planning Organization of Turkey
Turkish Accelerator Center (TAC) Infrared (IR) Free Electron Laser facility (FEL) supported by State Planning Organization (SPO) of Turkey will be based on 15-40 MeV energy range electron linac and two different undulators with 2.5 cm and 9 cm period lengths in order to obtain FEL in 2-250 micron wavelength range. The electron linac will consist of two superconducting ELBE modules which houses two 9-cell TESLA cavity in one module and can operate in cw mode. The electron bunches in cw mode which are compatible with the main linac will be provided by a thermionic gun and an injector system which is totally based on normal conducting technology. In this study the injector design for TAC IR FEL is represented and beam dynamics issues were discussed for suitable injection to first accelerating module.
ANL, Argonne
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
The corrective steering algorithm in TRACK has been recently updated to be more realistic. A simplified formalism will be presented along with the method of implementation. As an important application, the algorithm was used to determine the number of correctors and monitors required for the front-end of the HINS project at Fermilab. The algorithm allowed us also to find the optimum locations for the correctors and monitors as well as the required corrector field strength and the required monitor precision for an effective correction. This correction procedure could be easily implemented in an accelerator control-room for real-time machine operations.
UMAN, Manchester
CERN, Geneva
The upgrade of the normal conducting REX-ISOLDE heavy ion accelerator at CERN, under the HIE-ISOLDE framework, proposes the use of superconducting (SC) quarter-wave resonators (QWRs) to increase the energy capability of the facility from 3 MeV/u to beyond 10 MeV/u. A beam dynamics study of a lattice design comprising SC QWRs and SC solenoids has confirmed the design's ability to accelerate ions, with a mass-to-charge ratio in the range 2.5 < A/q < 4.5, to the target energy with a minimal emittance increase. We report on the development of this study to include the implementation of realistic fields within the QWRs and solenoids. A preliminary error study is presented in order to constrain tolerances on the manufacturing and alignment of the linac.
Imperial College of Science and Technology, Department of Physics, London
The Muon Ionisation Cooling Experiment (MICE) at RAL will be the first apparatus to study muon cooling at high precision. Muons are produced along a transport beamline in a super-conducting solenoid via pion decay. The final beam emittance is generated by tuning the quadrupoles for beam size matching. The beam angular divergence is matched in a variable-thickness diffuser, which is a re-entrant mechanism inside the first solenoid, automatically changeable in few minutes from 0 to 4X0. The initial normalized emittance of the beam (few mm rad) will be inflated up to 10 mm rad in order to cover the (eN,P) matrix required by the experiment. Details of beamline tuning are presented.
CERN, Geneva
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
The emission of Synchrotron Radiation in the CLIC BDS is one of the major limitations of the machine performance. An extensive revision of this phenomenon is presented with special emphasis on the IP solenoid.
UCR, Riverside, California
The Muon Ionization Cooling Experiment (MICE) is being built at the Rutherford Appleton Laboratory (RAL) to test ionization cooling of a muon beam. Successful demonstration of cooling is a necessary step along the path toward creating future high intensity muon beams in either a neutrino factory or muon collider. MICE will reduce the transverse emittance of the beam by 10%, and spectrometers using particle physics techniques will measure the emittance reduction with an absolute precision of 0.1%. This measurement will be done with scintillating fiber tracking detectors nested inside solenoid magnets on either side of the cooling channel. Each fiber tracker contains five stations with 3 layers of fibers rotated 120 degrees with respect to each other, thereby allowing reconstruction of hit points along the path of the muons. Light is carried from the active fiber volume by clear waveguide fibers where it is detected using VLPCs (Visible Light Photon Counters). The details of the tracker commissioning using cosmic rays will be discussed in addition to the status and performance of the readout electronics*.
*Submitted on behalf of the MICE collaboration.
UMD, College Park, Maryland
ANL, Argonne
Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office.
Single foil OTR and two foil OTR interferometry have been successfully used to measure the size and divergence of electron beams with a wide range of energies. To measure rms emittance, two cameras are employed: one focused on the foil to obtain the spatial distribution of the beam, the other focused to infinity to obtain the angular distribution. The beam is first magnetically focused to a minimum size in directions which are orthogonal to the propagation axis, using a pair of quadrupoles. Then simultaneous measurements of the rms size (x,y) and divergence (x’,y’) of the beam are made. However, in the process of a quadrupole scan, the beam can go through a spot size minimum, a divergence minimum and a waist, i.e. the position where the cross-correlation term is zero. In general, the beam size, divergence and focusing strength for each of these conditions are different. We present new algorithms that relate the beam and magnetic parameters to the rms emittance for each of these three cases. We also compare the emittances, obtained using our algorithms and measurements made at the ANL AWA facility, with those produced by computer simulation.
CLASSE, Ithaca, New York
Commissioning of a new high brightness electron source for the Energy Recovery Linac at Cornell University is currently underway. Despite the fact that the beam dynamics in this portion of the accelerator is space-charge dominated, a fundamental understanding of the machine linear optics is crucial in that it determines the effectiveness of space-charge emittance compensation methods, as well as provides the means to achieving various beam parameters such as beam length and energy spread. Here we introduce a new numerical tool being used in the commissioning of the injector that provides linear optics matrix calculation using field maps for various optical elements.
LBNL, Berkeley, California
Funding: This research was performed under the auspices of the U.S. DOE at the Lawrence Livermore and Lawrence Berkeley National Laboratories under Contracts No. DE-AC52-07NA27344 and No. DE-AC02-05CH11231.
A recent theory in Ref. * analyzes small-amplitude oscillations of the transverse beam centroid (center of mass) in solenoidal transport channels. This theory employs a transformation to a rotating Larmor frame to simply express the centroid response to mechanical misalignments (transverse center displacements and tilts about the of the longitudinal axis of symmetry) of the solenoid and initial centroid errors. The centroid evolution is expressed in terms of a superposition of the centroid evolving in the ideal aligned system plus an expansion in terms of "alignment functions" that are functions of only the ideal lattice with corresponding amplitudes set by the solenoid misalignment parameters. This formulation is applied to analyze statistical properties of beam centroid oscillations induced by solenoid misalignments. Results are compared to experiments at the NDCX experiment at the LBNL. It is found that contributions to oscillation amplitudes from tilts are significantly larger than contributions from offsets for expected parameters. Use of the formulation to optimally steer the centroid back on-axis with limited diagnostic measurements is also discussed.
* S.M. Lund, C.J. Wootton, and E.P. Lee, "Transverse centroid oscillations in solenoidally focused beam transport lattices," accepted for publication, Nuc. Inst. Meth. A.
LBNL, Berkeley, California
Analytical formula of the 6X6 transfer matrix of a magnetic solenoid is derived. As an example, analytical and numerical study of a bunch compressor consists of such solenoids is presented.
UCR, Riverside, California
Funding: Work supported by the United States Department of Energy under Grant No. DE-FG02-07ER41487.
The RFOFO ring is considered to be one of the most promising six-dimensional cooling channels proposed for the future Muon Collider. It has a number of advantages over other cooling channels, but also certain drawbacks. The injection and extraction, the absorber overheating, and the bunch train length are among the main issues. A number of simulations of a possible solution to these problems, the RFOFO helix, commonly referred to as the Guggenheim channel, were carried out and their results are summarized. The issue of the RF breakdown in the magnetic field is addressed, and the preliminary results of the simulation of the lattice with magnetic coils in the irises of the RF cavities are presented.
JLAB, Newport News, Virginia
UMD, College Park, Maryland
BNL, Upton, Long Island, New York
Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office
Longitudinal space-charge waves can introduce energy perturbations into charge particle beams and degrade the beam quality, which is critical to many modern applications of particle accelerators. Although many longitudinal phenomena arising from small perturbations can be explained by a one-dimensional cold fluid theory, nonlinear behavior of space-charge waves observed in experiments has not been well understood. In this paper, we summarize our recent investigation by means of more detailed measurements and self-consistent simulations. Combining the numerical capability of a PIC code, WARP, with the detailed initial conditions measured by our newly developed time resolved 6-D phase space mapping technique, we are able to construct a self consistent model for studying the complex physics of longitudinal dynamics of space-charge dominated beams. Results from simulation studies suggest that the unexplained nonlinear behavior of space-charge waves may be due to transverse mismatch or misalignment of beams.
UMD, College Park, Maryland
BNL, Upton, Long Island, New York
Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office
Beam matching is critical for avoiding envelope mismatch oscillations that can lead to emittance growth and halo formation, especially if the beam has significant space charge. The University of Maryland Electron Ring (UMER) is a research storage ring that is designed for scaled studies that are applicable to many larger machines. Using 10 keV electron beams at relatively high current (0.6 100 mA), space charge forces are relatively strong. Matching of the UMER beam is rendered difficult by the space charge, the crowdedness of the lattice, and especially the unique injection scheme where an offset oversized quadrupole is shared between the ring and the injector. In this paper we discuss several schemes for optimizing the matching at injection, both analytical and beam-based, which we test using particle-in-cell simulations with the code, WARP. Comparison to UMER experimental data is provided where available.
LBNL, Berkeley, California
TU Darmstadt, Darmstadt
GSI, Darmstadt
LLNL, Livermore, California
Ion acceleration from high-intensity, short-pulse laser irradiated thin foils has attracted much attention during the past decade. The emitted ion and, in particular, proton pulses contain large particle numbers (exceeding a trillion particles) with energies in the multi-MeV range and are tightly confined in time (< ps) and space (source radius a few micrometers). The generation of these high-current beams is a promising new area of research and has motivated pursuit of applications such as tabletop proton sources or pre-accelerators. Requirements for an injector are controllability, reproducibility and a narrow (quasi-monoenergetic) energy. However, the source provides a divergent beam with an exponential energy spectrum that exhibits a sharp cutoff at its maximum energy. The laser and plasma physics group of the TU Darmstadt, in collaboration with GSI and LBNL, is studying possibilities for transport and RF capture in conventional accelerator structures. First results on controlling laser-accelerated proton beams are presented, supported by WARP simulations.
Muons, Inc, Batavia
Hampton University, Hampton, Virginia
JLAB, Newport News, Virginia
Fermilab, Batavia
Funding: Work supported in part in part by DOE contract DE-AC02-07CH11359 and DOE STTR Grant DE-FG02-05ER86253
In order to achieve cooling of muons in addition to 6D helical cooling channel (HCC) [1], we develop a technique based on a parametric resonance. The use of parametric resonances requires alternating dispersion, minimized at locations of thin absorbers, but maximized in between in order to compensate for chromatic aberrations [2]. These solutions can be combined in an Epicyclic Helical Cooling Channel (EHCC) that meets requirements of alternating dispersion of beam periodic orbit with best conditions for maintenance of stable beam transport in a continuous solenoid-type field [3]. We discuss here basic features and new simulation results for EHCC.
SLAC, Menlo Park, California
IHEP Beijing, Beijing
Funding: Work supported in part by the DOE Contract DE-AC02-76SF00515. This work was performed in support of the LCLS project at SLAC.
XAL, a high-level application framework originally developed by Spallation Neutron Source (SNS), has been adapted by the Linac Coherent Light Source (LCLS) project. The work includes proper relational database schema modification to better suit XAL configuration data requirement, addition of new device types for LCLS online modeling purpose, longitudinal coordinate system change to better represent the LCLS electron beam rather than proton or ion beam in the original SNS XAL design, intensively benchmark with MAD and present SLC modeling system for the online model, and various new features to the XAL framework. Storing online model data in a relational database and providing universal access methods for other applications is also described here.
ANL, Argonne
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
An energy upgrade project of the ATLAS heavy ion linac at ANL includes a new cryomodule containing seven {10}9 MHz β=0.15 quarter-wave superconducting cavities to provide an additional 15 MV voltage to the existing linac. Several new features have been incorporated into both the cavity and cryomodule design. For example, the primary feature of the cryomodule is a separation of the cavity vacuum space from the insulating vacuum. The cavities are designed in order to cancel the beam steering effect due to the RF field. The cryomodule was designed and built as a prototype for the driver linac of the Facility for Rare Isotope Beams (FRIB). Similar design can be effectively used in the SC proton linac for the Project X at FNAL. Currently, we are working on cryomodule assembly and final preparation of cryogenics, RF, vacuum and other subsystems for off-line tests. The initial commissioning results will be reported.
Fermilab, Batavia
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The present FNAL Linac H- injector has been operational since 1978 and consists of a magnetron H- source and a 750-keV Cockcroft-Walton Accelerator. The proposed upgrade to this injector is to replace the present magnetron source having a rectangular aperture with a circular aperture, and to replace the Cockcroft-Walton with a 200-MHz RFQ. Operational experience at other laboratories has shown that the upgraded source and RFQ will be more reliable and require less manpower than the present system.
Fermilab, Batavia
Funding: Work performed by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The High Intensity Neutrino Source (HINS) linac R&D program at Fermilab is constructing a first-of-a-kind superconducting H- linac. The machine will demonstrate acceleration of high intensity beam using superconducting spoke cavities, solenoidal focusing optics throughout for control of halo growth, and operation of many cavities from a single high power rf source for acceleration of non-relativistic particles. The ion source and RFQ are operational with beam and the 10 MeV room temperature cavity section is being assembled. Superconducting spoke cavity testing is proceeding. The overall status and outlook of the HINS program is presented.
CIAE, Beijing
FZJ, Jülich
The 10 mA, 40keV H- pulsed injection line for the CIAE 10 MeV CRM cyclotron has two main operation modes for bunched beams: delivering 5 mA CW beam or chopped pulse with more than 100uA. Chopped pulse is achieved by placing behind the 70.5 MHz bunching cavity a sinusoidal transverse deflecting cavity with frequency of 2.2 MHz, 1/32 of the bunching frequency. Particles outside the wanted ±3° phase width @ 2.2 MHz, corresponding to ±90° @ 70.5 MHz, are either absorbed in a 50cm drift after chopper or at round slit1, 1cm aperture. Time dependence of sinusoidal chopping field causes RMS emittance increase by a factor 3 and changes twiss parameter alpha by a factor 2 before the round slit1. Solenoid couples motion in transversal planes, but equalizes both RMS emittances. Particle tracking results are presented for the chopped pulse, showing longitudinal-transverse coupling in the deflector and equalization of RMS emittances in the solenoid. Optimised focusing strength leads to about 1 % transmission efficiency for the chopped pulse. The CRM inflector receives 2.4 ns long pulse at about 4.4 MHz repetition rate, 1/16 of the RF frequency.
JINR, Dubna, Moscow Region
IBA, Louvain-la-Neuve
C400 is compact superconducting isochronous cyclotron for carbon beam therapy designed by IBA, Louvain-La-Neuve (Belgium) in collaboration with JINR, Dubna (Russia). The cyclotron can accelerate all ions with charge to mass ratio 0.5. Protons are accelerated as single charge 2H+ molecules and extracted by stripping at 270 MeV. All other ions are extracted by an electrostatic deflector at 400 MeV/u. The final layout of the axial injection beam line of C400 cyclotron is given. Two ion sources for production of 12C6+ ions and Alphas beams are located at the horizontal part of the channel before both side of the combination vertical magnet. The third ion source for the production of 2H+ is placed in straight line on the vertical axis. The rotational symmetry of the beam is reestablished with the help of one quadrupole lens placed just after analyzing magnet. The beam focusing at the vertical part of the channel is provided by three solenoidal lenses instead of four quadrupoles used in the previous version of beam line. The results of simulation of ion beams transport in the axial injection channel are presented.