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Muon Collider: Muon Generation, Capture and Cooling

Description: A {mu}{sup +} -{mu}{sup -} collider requires a high-intensity proton source for {pi}-production, a high-acceptance {pi}-{mu} decay channel, a {mu}-cooling system, a rapid acceleration system, and a high-luminosity collider ring for the collision of short, intense {mu}{sup +} -{mu}{sup -} bunches. Critical problems exist in developing and compressing high-energy proton bunches for producing {pi}�s, in capturing {pi}�s and their decay {mu}�s, and in cooling {mu}�s into a compressed phase-space at which high luminosity collisions are possible. These problems and some possible solutions are discussed; the current {mu}{sup +} -{mu}{sup -} collider research program is described
Date: February 16, 1999
Creator: Neuffer, David
Partner: UNT Libraries Government Documents Department

Plasma and Beam Production Experiments with HYBRIS, aMicrowave-assisted H- Ion

Description: A two-stage ion source concept had been presented a few years ago, consisting of a proven H- ion source and a 2.45-GHz Electron Cyclotron-Resonance (ECR) type ion source, here used as a plasma cathode. This paper describes the experimental development path pursued at Lawrence Berkeley National Laboratory, from the early concept to a working unit that produces plasma in both stages and creates a negative particle beam. Without cesiation applied to the second stage, the H{sup -} fraction of this beam is very low, yielding 75 micro-amperes of extracted ion beam current at best. The apparent limitations of this approach and envisaged improvements are discussed.
Date: September 13, 2006
Creator: Keller, R. AUTHOR-Kwan, S.; Hahto, S.; Regis, M. & Wallig, J.
Partner: UNT Libraries Government Documents Department

High efficiency muon beam

Description: Aspects of muon beams pertinent to the establishment of an effective nucleon structure facility are discussed and a preliminary design for such a beam at NAL is advanced. The optical properties, duty factor and proton beam source are already able to be sharply specified, but the pion and muon transports need more work to be optimal. It is already clear, however, that efficiency gains of at least 20 can be made and probably- factors of 50 or even 100 are not impossible. Beam/halo ratios can probably be raised to 14: 1 with proper spoilers. Most important of all, the effective beam time can be raised an order of magnitude over present prospects by establishing a separate source of protons for a muon beam by means of a split or pulsed switch in the present neutrino beam time. (auth)
Date: September 1, 1973
Creator: Kirk, T.
Partner: UNT Libraries Government Documents Department

Target and collection optimization for muon colliders

Description: To achieve adequate luminosity in a muon collider it is necessary to produce and collect large numbers of muons. The basic method used in this paper follows closely a proposed scheme which starts with a proton beam impinging on a thick target ({approximately} one interaction length) followed by a long solenoid which collects muons resulting mainly from pion decay. Production and collection of pions and their decay muons must be optimized while keeping in mind limitations of target integrity and of the technology of magnets and cavities. Results of extensive simulations for 8 GeV protons on various targets and with various collection schemes are reported. Besides muon yields results include-energy deposition in target and solenoid to address cooling requirements for these systems. Target composition, diameter, and length are varied in this study as well as the configuration and field strengths of the solenoid channel. A curved solenoid field is introduced to separate positive and negative pions within a few meters of the target. This permits each to be placed in separate RF buckets for acceleration which effectively doubles the number of muons per bunch available for collisions and increases the luminosity fourfold.
Date: January 10, 1996
Creator: Mokhov, N.V.; Noble, R.J. & Van Ginneken, A.
Partner: UNT Libraries Government Documents Department

The production and transport of radioactive {sup 17}F at ATLAS for research

Description: A secondary beam of radioactive {sup 17}F was produced at the ATLAS accelerator and delivered to an experimental target station with an intensity of as much as 5{circ}10{sup 5} ions/s for use in the research program. Beams of {sup 17}F were produced via the p({sup 17}O, {sup 17}F)n or d({sup 16}O, {sup 17}F)n reactions by bombarding a gas-filled cell with up to 300 pnA beams of {sup 17}O or {sup 16}O from the ATLAS superconducting linac. The gas target, with HAVAR windows, was maintained at pressures as high as 500 Torr. The beam quality was dominated by small-angle scattering in the gas cell windows, by the reaction kinematics and beamline acceptance. Detailed beam parameters are presented. Plans for relocation of the target to allow improved capture efficiency and acceleration or de-acceleration of the secondary beam will also be discussed.
Date: June 1, 1997
Creator: Harss, B.; Berger, J.C. & Borasi, F.
Partner: UNT Libraries Government Documents Department

Isobar Separators for Radioactive Ion Beam Facilities

Description: A radioactive ion beam facility - in short a RIB facility - produces ions of short-lived nuclei and accelerates them to energies of 0.1�10 MeV per nucleon or even higher. In this process it is important that the resulting RIB beams are free from nuclei of neighboring isobars or of neighboring elements. This task requires the production and ionization of the nuclei of interest as well as separating them from all others with a high-mass resolving power and small-mass cross contaminations. When constructing such a facility it also is very important to find ways that allow the accelerated ions to be provided to different experiments at least quasi simultaneously.
Date: October 5, 1998
Creator: Garrett, J.D. & Wollnik, H.
Partner: UNT Libraries Government Documents Department

Multi-kiloampere, electron-beam generation from bare aluminum photo-cathodes driven by an ArF laser

Description: An electron-beam-pumped laser operating at ArF (193 nm) producing up to 5.0 joules in a 150-ns pulse has been used to illuminate micro-machined aluminum cathodes. The cathode was pulsed from 2.25- up to 2.95-MV across a 20-cm-AK gap producing fields up to 145 kV/cm using REX (a 4-MeV, 5-kA, 100-ns pulsed diode). Extracted current versus laser power gives a quantum efficiency increasing with power density from 0.07 to 0.11%. The present work is significant in that the cathode operates in the presence of out-gassing materials with a background vacuum pressure in the mid 10{sup {minus}6} torr region and 100-ns-long electron beams of up to 3 kA have been produced. Both emission limited (current follows laser pulse) and space-charge-limited (current follows pulsed power) regimes have been studied up to {approximately} 50 A/cm{sup 2} by varying the cathode diameter. The beam temperature has been measured to be < 5 eV and directly compared in the same experimental setup to velvet based cathodes that measure {approximately} 100 eV.
Date: October 1, 1997
Creator: Carlson, R.L.; Ridlon, R.N.; Seitz, G.J. & Hughes, T.P.
Partner: UNT Libraries Government Documents Department

The physics potential of neutrino beams from muon storage rings

Description: High-intensity neutrino beams could be produced using a very intense muon source, and allowing the muons to decay in a storage ring containing a long straight section. Taking the parameters of muon source designs that are currently under study for future high luminosity muon colliders, the characteristics of the neutrino beams that could be produced are discussed and some examples of their physics potential given. It is shown that the neutrino and antineutrino beam intensities may be sufficient to produce hundreds of neutrino interactions per year in a detector on the far side of the Earth.
Date: December 1, 1997
Creator: Greer, S.
Partner: UNT Libraries Government Documents Department

High intensity muon storage rings for neutrino production: Lattice design

Description: Five energies, 250, 100, 50, 20, and 10 GeV, have been explored in the design of a muon storage ring for neutrino-beam production. The ring design incorporates exceptionally long straight sections with large beta functions in order to produce an intense, parallel neutrino beam via muon decay. To emphasize compactness and reduce the number of muon decays in the arcs, high-field superconducting dipoles are used in the arc design.
Date: May 1, 1998
Creator: Johnstone, C>
Partner: UNT Libraries Government Documents Department

Development of a 130-mA, 75-kV high voltage column for high-intensity dc proton injectors

Description: A reliable high-voltage (HV) column has been developed for dc proton injectors with applications to high-intensity cw linacs. The HV column is coupled with a microwave-driven plasma generator to produce a 75-keV, 110-mA dc proton beam. Typical proton fraction from this source is 85--90%, requiring the HV column and accelerating electrodes to operate with a 130-mA hydrogen-ion beam current. A glow-discharge, which was caused by the ion source axial magnetic field, was initially observed in the HV column. This problem was solved by scaling the electron production processes, the magnetic field, and the HV column pressure into a favorable regime. A subsequent 168 hour reliability run on the 75-keV injector showed that the ion source (plasma generator and HV column) has >98% beam availability.
Date: December 1, 1997
Creator: Sherman, J.; Arvin, A.; Hansborough, L.; Hodgkins, D.; Meyer, E.; Schneider, J.D. et al.
Partner: UNT Libraries Government Documents Department

Inductive voltage adder (IVA) for submillimeter radius electron beam

Description: The authors have already demonstrated the utility of inductive voltage adder accelerators for production of small-size electron beams. In this approach, the inductive voltage adder drives a magnetically immersed foilless diode to produce high-energy (10--20 MeV), high-brightness pencil electron beams. This concept was first demonstrated with the successful experiments which converted the linear induction accelerator RADLAC II into an IVA fitted with a small 1-cm radius cathode magnetically immersed foilless diode (RADLAC II/SMILE). They present here first validations of extending this idea to mm-scale electron beams using the SABRE and HERMES-III inductive voltage adders as test beds. The SABRE experiments are already completed and have produced 30-kA, 9-MeV electron beams with envelope diameter of 1.5-mm FWHM. The HERMES-III experiments are currently underway.
Date: December 31, 1996
Creator: Mazarakis, M.G.; Poukey, J.W. & Maenchen, J.E.
Partner: UNT Libraries Government Documents Department

Pion Production and Targetry at {mu} {sup +} {mu} {sup -} Colliders

Description: Results of simulations of pion production and power dissipation by 8 to 30 GeV proton beams in co-axial and tilted targets of liquid gallium and platinum oxide, placed in a 20 T solenoid, are reported. Pion and muon distributions are followed through the matching solenoid and decay channel.
Date: January 1, 1998
Creator: Mokhov, N.V. & Van Ginneken, A.
Partner: UNT Libraries Government Documents Department

Production of high-brightness CW proton beams with very high proton fractions

Description: This paper demonstrates a new technique to significantly enhance the proton fraction of an ion beam extracted from a plasma ion source. We employ a magnetically confined microwave driven source, though the technique is not source-specific and can probably be applied equally effectively to other plasma sources such as Penning and multicusp types. Specifically, we dope the plasma with about 1% H{sub 2}O, which increases the proton fraction of a 45 keV 45 mA beam from 75 to 90% with 375W 2.45 GHz power to the source and from 84% to 92% for 500W when the source is operated under nonresonant conditions. Much of the remaining fraction of the beam comprises a heavy mass ion we believe to be N{sup +} impurity ions resulting from the conditions under which the experiments were performed. If so, this impurity can be easily removed and much higher proton fractions could be expected. Preliminary measurements show the additive has no adverse effect on the emittance of the extracted beam, and source stability is greatly improved.
Date: December 1, 1995
Creator: Spence, D.; McMichael, G.; Lykke, K.R.; Schneider, J.D.; Sherman, J.; Stevens, R. Jr. et al.
Partner: UNT Libraries Government Documents Department

Production of U{sup 92+} with an EBIT

Description: A super electron beam ion trap has been used to produce bare U{sup 92+} ions at an electron beam energy of 198 keV. Evaporative cooling with light ions was used to trap a population of 5 {times} 10{sup 4} highly charged uranium ions for many seconds and reduce their temperature to less than 2q eV, suggesting that a very low emittance source of these ions is possible. Roughly 10 U{sup 92+} and 500 U{sup 91+} ions were present in the Super EBIT as determined from x-ray emission spectra of the trapped ions.
Date: December 1, 1995
Creator: Marrs, R.E.
Partner: UNT Libraries Government Documents Department

Oak Ridge 25URC tandem accelerator 1994 SNEAP lab report

Description: The 25URC tandem accelerator is still in shut-down mode until the facility is reconfigured to produce radioactive ion beams (RIBs). Again, the authors have operated approximately 200 hours for ion implantation studies in support of RIB development. Operation of the accelerator has been generally very reliable with most problems being associated with power supplies and components located outside the accelerator. The major operational problem this year was the development of internal shorts in the coils of the energy-analyzing magnet which caused beam instability. The major development activity for the tandem accelerator was the replacement of the corona-point voltage-grading system with resistors. Several milestones for the RIB project have been met since SNEAP 1993. The high-voltage platforms have been built and tested at the required 300 kV. Most equipment has been installed on the platforms so that the first beam can be developed using the Mark I target-ion source. This ion source was characterized on the ion source test facility before moving it to the platform. The second-stage mass-separator magnets have been specified and the contract has been awarded to Sigma Phi. The final optics design for the beam line from the second-stage separator to the tandem accelerator is being completed and equipment and controls are being procured.
Date: December 31, 1994
Creator: Alton, G.D.; Dinehart, M.R. & Dowling, D.T.
Partner: UNT Libraries Government Documents Department

Decision support facility for the APS control system.

Description: The Advanced Photon Source is now in its fifth year of routine beam production. The EPICS-based [1] control system has entered the phase in its life cycle where new control algorithms must be implemented under increasingly stringent operational and reliability requirements. The sheer volume of the control system ({approx}270,000 records, {approx}145 VME-based input-output controllers (IOCs), and {approx}7,000,000 lines of EPICS ASCII configuration code), presents a daunting challenge for code maintenance. The present work describes a relational database that provides an integrated view of the interacting components of the entire APS control system, including the IOC low-level logic, the physical wiring documentation, and high-level client applications. The database is extracted (booted) from the same operational CVS repository as that used to load the active IOCs. It provides site-wide decision support facilities to inspect and trace control flow and to identify client (e.g., user interface) programs involved at any selected point in the front-end logic. The relational database forms a basis for generalized documentation of global control logic and its connection with both the physical I/O and with external high-level applications.
Date: November 12, 2001
Creator: Dohan, D. A.
Partner: UNT Libraries Government Documents Department

Two frequency operation of the Argonne ECR ion source.

Description: Performance of the Argonne ECR ion source has been improved through the use of two frequency heating--the primary frequency of 14 GHz from a klystron and the second frequency from a traveling wave tube amplifier (TWTA) with a tunable range of 11.0--13.0 GHz. Source output as well as stability have been improved with a shift to higher charge states observed. A larger separation between the two operating frequencies has demonstrated improved beam production as well as greater stability. The addition of 60 watts at 10.85 GHz produced a 69% increase in O{sup 7+} beam production, whereas a similar increase to the 14 GHz RF power alone, without the addition of a second frequency, produced only a 20% increase in beam production. Use of a second frequency has increased the intensity of the medium charge states by 50-100% ({sup 56}Fe{sup 13+}: 10.6 {yields} 17.4 e{mu}A; {sup 86}Kr{sup 15+}: 65 {yields} 120 e{mu}A) and the higher charge states a factor of 2 to 5 ({sup 56}Fe{sup 17+}: 1.15 {yields} 6.40 e{mu}A; {sup 238}U{sup 37+}: 2.0 {yields} 3.0 e{mu}A). Operational modes and results will be presented.
Date: August 1, 2002
Creator: Vondrasek, R. C.; Scott, R. H. & Pardo, R. C.
Partner: UNT Libraries Government Documents Department

Neutrino oscillation results from MINOS

Description: The Main Injector Neutrino Oscillation Search (MINOS) long-baseline experiment has been actively collecting beam data since 2005, having already accumulated 3 x 10{sup 20} protons-on-target (POT). MINOS uses the Neutrinos at the Main Injector (NuMI) neutrino beam measured in two locations: at Fermilab, close to beam production, and 735 km downstream, in Northern Minnesota. By observing the oscillatory structure in the neutrino energy spectrum, MINOS can precisely measure the neutrino oscillation parameters in the atmospheric sector. These parameters were determined to be |{Delta}m{sub 32}{sup 2}| = 2.74{sub -0.26}{sup +0.44} x 10{sup -3} eV{sup 2}/c{sup 4} and sin{sup 2}(2{theta}{sub 23}) &gt; 0.87 (68% C.L.) from analysis of the first year of data, corresponding to 1.27 x 10{sup 20} POT.
Date: August 1, 2007
Creator: Sousa, Alexandre
Partner: UNT Libraries Government Documents Department

Beam dynamics enhancement due to accelerating field symmetrization in the BNL/SLAC/UCLA 1.6 cell S-band photocathode RF gun

Description: A 1.6 cell photocathode S-Band gun developed by the BNL/SLAC/UCLA collaboration is now in operation at the Brookhaven Accelerator Test Facility (ATF). One of the main features of this RF gun is the symmetrization of the RF coupling iris with an identical vacuum pumping port located in the full cell. The effects of the asymmetry caused by the RF coupling iris were experimentally investigated by positioning a metallic plunger at the back wall of the vacuum port iris. The higher order modes produced were studied using electron beamlets with 8-fold symmetry. The 8-fold beamlets were produced by masking the laser beam. These experimental results indicate that the integrated electrical center and the geometrical center of the gun are within 175 {micro}m. Which is within the laser alignment tolerance of 250 {micro}m.
Date: July 1997
Creator: Palmer, D. T.; Miller, R. H.; Wang, X. J. & Ben-Zvi, I.
Partner: UNT Libraries Government Documents Department

Working group II report: Production and dynamics of high brightness beams

Description: This paper summarizes the main discussions of the Working Group on the Production and Dynamics of High Brightness Beams. The following topics are covered in this paper. Proposed new electron sources and needed research on existing sources is covered. The discussions on issues relating to the description of phase space on non-thermalized electron beam distributions and the theoretical modeling on non-thermalized electron beam distributions is presented. Finally, the present status of the theoretical modeling of beam transport in bends is given.
Date: December 31, 1996
Creator: Sheffield, R.L.
Partner: UNT Libraries Government Documents Department

ECR Ion Source Developments at the Oak Ridge National Laboratory

Description: New techniques for enhancing the performances of electron cyclotron resonance (ECR) ion sources are being investigated at the Oak Ridge National Laboratory. We have utilized the multiple discrete frequency technique to improve the charge state distributions extracted from conventional magnetic field geometry ECR source by injecting three frequencies into the source. A new flat central magnetic field concept, has been incorporated in the designs of a compact all-permanent-magnet source for high charge-state ion beam generation and a compact electromagnetic source for singly ionized radioactive ion beam generation for use in the Holifield Radioactive Ion Beam Facility (HRIBF) research program. A review of the three frequency injection experiments and descriptions of the design aspects of the "volume-type" ECR ion sources will be given in this report.
Date: October 5, 1998
Creator: Alton, G.D.; Liu, Y. & Meyer, F.W.
Partner: UNT Libraries Government Documents Department