Bulletin of the American Physical Society
2005 APS April Meeting
Saturday–Tuesday, April 16–19, 2005; Tampa, FL
Session T13: Intermediate Energy Accelerators, Radiation Sources, and New Acceleration Methods |
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Sponsoring Units: DPB Chair: Gerald Dugan, Cornell University Room: Marriott Tampa Waterside Room 12 |
Monday, April 18, 2005 1:30PM - 1:42PM |
T13.00001: Barrier RF Stacking in the Fermilab Main Injector Hai Zheng, D. Michael, W. Chou, J. Griffin, J. MacLachlan, K.-Y. Ng, D. Wildman, Y. Mori, A. Takagi A novel wideband RF system, nicknamed ``Barrier RF,'' has been designed, fabricated and installed in the Fermilab Main Injector. The cavity is made of seven Finemet cores, and the modulator made of two bipolar high-voltage fast solid-state switches. The system can deliver $\pm 7\;$kV square pulses at 90~kHz. The main application is to stack two proton batches injected from the Booster and squeeze them into the size of one so that the bunch intensity can be doubled. This increased intensity will be of significant benefit to experiments like MINOS in which the 120~GeV Main Injector beam is extracted into the NuMI beam line to generate neutrinos. High intensity beams have been successfully stacked and accelerated to 120~GeV with small losses. The problem of large longitudinal emittance growth is the focus of the present study. An upgraded system with two barrier RF cavities for continuous stacking is under construction. This work is part of the US-Japan collaborative agreement. [Preview Abstract] |
Monday, April 18, 2005 1:42PM - 1:54PM |
T13.00002: Brookhaven Super Neutrino Beam Project Jie Wei, Wu-Tsung Weng, Yong Yung Lee, Nicholaos Tsoupas, Deepak Raparia, S.Y. Zhang Super neutrino beam facilities are used to accurately determine the neutrino mixing amplitudes and phase, as well as the CP violation parameters with the long distance and wideband nature of the neutrino beam for the observation of several oscillations from one species of the neutrino to the other. The Super Neutrino Beam Project was proposed at the Brookhaven National Laboratory based on an upgrade of the AGS proton facility from the current 0.14 MW to over 1 MW beam power. The project consists of three major parts: a 1.5 GeV superconducting RF linac that replaces the booster as injector for the AGS, performance upgrade of the AGS itself for a higher intensity and repetition rate, and finally the target and horn system for the neutrino production. This talk gives an overview of the project with emphasis on the design consideration to achieve high intensity and low beam loss for the accelerator systems. [Preview Abstract] |
Monday, April 18, 2005 1:54PM - 2:06PM |
T13.00003: Center for Accelerator Science and Technology at MIT -- A New Initiative Stephen Steadman MIT is proposing to establish a new interdisciplinary Center for Accelerator Science and Technology (CAST) led by faculty from across the Schools of Science and Engineering that would carry out frontier R{\&}D and have a strong educational program. The initial research focus includes development of technologies relevant to major accelerator initiatives such as the JLab 12 GeV Upgrade, RHIC II, e-RHIC, the ILC, and a laser-seeded FEL light source. The MIT Bates Linear Accelerator Center, which will soon complete its role as a nuclear physics user facility, is foreseen as the major laboratory focus for CAST. The facility staff and polarized injector, electron accelerator and the South Hall storage ring are outstanding resources for investigating important problems in accelerator science and the facility provides a premier test facility for training students. The CAST proposal may be found at the URL: \href{http://www2.lns.mit.edu/cast/}{http://www2.lns.mit.edu/cast/}. [Preview Abstract] |
Monday, April 18, 2005 2:06PM - 2:18PM |
T13.00004: The AWA BPM Project Jen Hsin, Jon Walsh Our project investigates methods of studying the transverse electron beam profile at the Argonne Wakefield Accelerator (AWA). Currently we are testing the resolutions of two beam position measurement systems: direct imaging using Yttrium Aluminum Garnet (YAG) crystal, and the Beam Position Monitoring (BPM) system. The ultimate goal is to employ a dependable and high-resolution beam position measuring system to study the accelerating capability of the wakefield structure. [Preview Abstract] |
Monday, April 18, 2005 2:18PM - 2:30PM |
T13.00005: Terahertz Coherent Synchrotron Radiation in the MIT-Bates South Hall Ring Fuhua Wang, Dan Cheever, Manouchehr Farkhondeh, Wilbur Franklin, William Graves, Ernie Ihloff, Richard Milner, Chris Tschalaer, Jan Van der Laan, Defa Wang, Dong Wang, Abbi Zolfaghari, Townsend Zwart, Larry Carr, Boris Podobedov, Fernando Sannibale We investigate the terahertz coherent synchrotron radiation (CSR) potential of the South Hall Ring (SHR) at MIT-Bates Linear Accelerator Center. The SHR is equipped with a unique single cavity, 2.856 GHz RF system. The high RF frequency is advantageous for producing short bunch length and for having higher bunch current threshold to generate stable CSR. Combining with other techniques such as external pulse stacking cavity, femtosecond laser slicing, the potential for generating ultra-stable, high power, broadband terahertz CSR is very attractive. Our first research effort will be the operation of low momentum compaction (alfa) lattice and stable CSR radiation generation from the existing SHR. Initial tests of low alfa manipulation and bunch length measurements are presented. [Preview Abstract] |
Monday, April 18, 2005 2:30PM - 2:42PM |
T13.00006: Angiography employing channeling radiation or coherent bremsstrahlung Herbert Uberall Angiography (imaging of coronary arteries) using synchrotron radiation has been carried out at the Stanford and later the Brookhaven Synchrotron. Digital subtraction angiography (DSA) with a contrast agent based on iodine is used above and below the K-edge (33.16 keV) employing a monochromatized beam of intensity reduced by a thousand. Channeling radiation or coherent bremsstrahlung furnish quasi-monochromatic beams, allowing efficient DSA at a photon flux of ten to the twelfth photons/sec. This requires an about 100 MeV electron linac for channeling radiation, or (better) an about 20 MeV linac for coherent bremsstrahlung. In the latter case, a large, broad incoherent bremsstrahlung peak accompanies the monochromatic spike (leading to inadmissible overexposure of the patient), but with the use of Kumakhov's capillary optics (see S. B. Dabagov, Physics Uspekhi 46, 2003, 1053-1075) the low-energy spiked radiation can be deflected towards the patient, while the incoherent peak continues forward, avoiding the patient who is placed several meters from the source. [Preview Abstract] |
Monday, April 18, 2005 2:42PM - 2:54PM |
T13.00007: Amplifying Laser Radiation by an Implosion inside a Reflecting Capillary Liner Friedwardt Winterberg It is shown that the energy of a pulsed laser beam can be amplified by orders of magnitude by letting it pass through an imploding capillary liner possessing a high wall reflectivity. The implosion can be accomplished with the pinch effect, letting a large current flow over the liner surface, or by the ablation of its outer surface through a burst of soft X-rays. If the inner radius of the liner can be imploded thirty-fold, the laser energy would be increased a thousand-fold. Because the amplification is through the conversion from longer to shorter wavelengths, the concept has the potential for intense short wavelength pulsed laser beams. The most important application of this laser amplification scheme seems to be for the fast ignition of thermonuclear microexplosions. [Preview Abstract] |
Monday, April 18, 2005 2:54PM - 3:06PM |
T13.00008: Electromagnetic Radiation of a Decelerating Moving de Broglie Particle: An Always Redshift J.X. Zheng-Johansson, P-I. Johansson %___Symbol Definition:___ \def\w{\omega}\def\g{\gamma}\def\W{{\mit \Omega}} \def\Lam {{\mit\Lambda}}\def\lam{\lambda} %___ABSTRACT:____ We observe that the electromagnetic (EM) radiation from the deceleration of a de Broglie particle as a moving source is always red-shifted, a phenomenon also clearly demonstrated in e.g. the moving hydrogen experiment by H.E. Ives and G.R. Stilwell, J. Opt. Soc. Am. {\bf 28}, 215(1938)[1]. The redshift in [1] is $\delta \lam/\lam_0 = (\sqrt{v^2}/c) /\g$ with $\g=1/ \sqrt{1-(v/c)^2}$, for the EM radiation of an orbiting electron decelerated by falling to an inner orbit which, following its hydrogen ion driven by an applied field, has a translational velocity $v$; $c$ is the velocity of light. In other words, by the redshift in radiation of the above type one is unable to tell whether the particle is moving away or toward the observer except for the $|v|$. Here the radiation frequency equals the de Broglie frequency $\w_d$ of a corresponding particle (effectively the difference between electron's initial and final states in [1]) which adds in full to the particle's mass $M$ as $M c^2 + (1/2)\hbar \w_d$. This is characteristically distinct from a conventional moving source which exhibits the usual Doppler effect informing the direction of source motion. The latter source is typically a charged object brought into oscillation of frequency $\W_a$ by an applied disturbance transverse to its EM wave propagation and source translation; $\W_a$ in general does not add coherently to the oscillator's mass. The two mechanisms can be clearer expounded in our particle formation scheme outlined e.g. in physics/0501037. [Preview Abstract] |
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