Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session G15: Accelerators and Lasers |
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Sponsoring Units: DPB Room: Plaza Court 4 |
Sunday, April 14, 2013 8:30AM - 8:42AM |
G15.00001: MICE, the international Muon Ionization Cooling Experiment Chris Heidt Ionization Cooling is the only practical solution to preparing high brilliance muon beams for a neutrino factory or muon collider. MICE is under development at the Rutherford Appleton Laboratory (UK). It is characterized by exquisite emittance determination by 6D measurement of individual particles, a cooling section comprising 23 MV of acceleration at 200 MHz and 3 liquid hydrogen absorbers totaling 1m of liquid hydrogen on the path of 140-240 MeV/c muons. Thebeam has already been commissioned successfully and first measurements of beam emittance performed. We are setting up for the final high precision emittance determination and the measurements of cooling in Li Hydrogen. The design offers opportunities to observe cooling with various absorbers and several optics configurations. Results will be compared with detailed simulations of cooling channel performance to ensure full understanding of the cooling process. Progress towards the full cooling experiment with RF re-acceleration will also be reported. [Preview Abstract] |
Sunday, April 14, 2013 8:42AM - 8:54AM |
G15.00002: Acoustic measurements of RF cavity breakdown Peter Lane, Pavel Snopok, Yagmur Torun, Alan Bross Current designs for muon cooling channels require high-gradient RF cavities to be placed in solenoidal magnetic fields in order to contain muons with large transverse emittances. It has been found that doing so reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields it would be helpful to have a diagnostic tool which can detect breakdown and localize the source of the breakdown inside the cavity. Acoustic data has been taken from the breakdown of various RF cavities being tested at the MuCool Test Area at Fermilab. This data has been used to develop a LabVIEW application that detects, archives, and analyzes acoustic signals received from an array of sensors placed on the outside of a cavity. The breakdown source location is estimated using time-of-arrival triangulation. The current state of the tool as well as plans for future tests on additional cavities will be presented. [Preview Abstract] |
Sunday, April 14, 2013 8:54AM - 9:06AM |
G15.00003: Development of tracking detector for transfer reactions with light beams at NSCL S. Ilyushkin, S. Ahn, D.W. Bardayan, J.A. Cizewski, B. Manning, P. O'Malley, S. Pain, F. Sarazin New beam tracking detectors based on low pressure multiwire proportional chambers are being developed to address the current limitations on position and timing resolution for light fast beams (Z \textless\ 10) at the National Superconducting Cyclotron Laboratory (NSCL). The improved beam spatial resolution at the target position will allow the possibility of performing transfer reaction studies with these very light exotic beams at the S800 spectrometer experimental facility. Prototype tests are currently being performed at the Holifield Radioactive Ion Beam Facility at the Oak Ridge National Laboratory. Results of these tests and comparisons with Garfield simulations will be presented. This work is supported by the U.S. Department of Energy. [Preview Abstract] |
Sunday, April 14, 2013 9:06AM - 9:18AM |
G15.00004: High-Intensity Continuous Wave Slow Positron Source at Jefferson Lab Serkan Golge, Branislav Vlahovic, Bogdan Wojtsekhowski We present a novel concept of an electron linac-based slow positron source with projected intensity on the order of 10$^{\mathrm{10}}$ slow e$^{\mathrm{+}}$/s. The key components of this concept are a Continuous Wave (CW) electron beam, a rotating positron-production target, a synchronized raster/anti-raster, a transport channel, and extraction of positrons into a field-free area through a magnetic field terminator plug for moderation in a solid Neon moderator. The feasibility calculations were completed in the framework of GEANT4 simulation and OPERA-3D magnetic field calculation code. [Preview Abstract] |
Sunday, April 14, 2013 9:18AM - 9:30AM |
G15.00005: Shock-wave proton acceleration from a hydrogen gas jet Nathan Cook, Igor Pogorelsky, Mikhail Polyanskiy, Marcus Babzien, Olivier Tresca, Chakra Maharjan, Peter Shkolnikov, Vitaly Yakimenko Typical laser acceleration experiments probe the interaction of intense linearly-polarized solid state laser pulses with dense metal targets. This interaction generates strong electric fields via Transverse Normal Sheath Acceleration and can accelerate protons to high peak energies but with a large thermal spectrum. Recently, the advancement of high pressure amplified $CO_2$ laser technology has allowed for the creation of intense ($10^{16} \frac{W}{cm^2}$) pulses at $\lambda \sim 10 \mu m$. These pulses may interact with reproducible, high rep. rate gas jet targets and still produce plasmas of critical density ($n_c \sim 10^{19} cm^{-3}$), leading to the transference of laser energy via radiation pressure. This acceleration mode has the advantage of producing narrow energy spectra while scaling well with pulse intensity. We observe the interaction of an intense $CO_2$ laser pulse with an overdense hydrogen gas jet. Using two pulse optical probing in conjunction with interferometry, we are able to obtain density profiles of the plasma. Proton energy spectra are obtained using a magnetic spectrometer and scintillating screen. [Preview Abstract] |
Sunday, April 14, 2013 9:30AM - 9:42AM |
G15.00006: Beamstrahlung Radiation for Beam-Beam Instability Rachid Ayad, Chaouki Boulahouache, Jamal H. Madani, Ibrahim S. Alobaidan, Abdelouahab Abdesselam, Giovanni Bonvicini, Mohammad A. Ahmad The Large Angle Beamstrahlung Monitor, LABM,to be installed at SuperKEKB accelerator, KEK Center, Japan, measures the intensity, spectrum and polarization of light emitted in the beam-beam interaction, which are related to beam-beam interaction parameters. The hopes for this device are that the study of the beam-beam interaction can change from being mostly model-driven to being mostly data-driven. Design issues are discussed, and a design close to final is presented. A list of possible measurements available at SuperKEKB is then discussed. [Preview Abstract] |
Sunday, April 14, 2013 9:42AM - 9:54AM |
G15.00007: Modeling of thermal effects in dielectric wakefield accelerators Peter Stoltz, Philippe Piot, Daniel Mihalcea, Francois Lemery An electron bunch passing through a dielectric-lined waveguide generates \v{C}erenkov radiation that can result in a high-peak axial electric field suitable for acceleration of a subsequent bunch. Axial fields beyond gigavolt-per-meter are attainable in structures with sub-mm sizes depending on the achievement of suitable electron bunch parameters. A promising configuration consists of using a planar dielectric structure driven by flat electron bunches. However, a main concern is the thermal loading in the dielectric that will result from a high repetition rate. We present numerical modeling of the temperature rise due to single and multiple bunch passings and also the thermal conduction and cooling requirements. [Preview Abstract] |
Sunday, April 14, 2013 9:54AM - 10:06AM |
G15.00008: Wake-Field Reduction in Hybrid Photonic Crystal Cavities Danny Rehn, Greg Werner, Carl Bauer, John Cary Photonic crystals (PhCs) have attractive properties for manipulating electromagnetic radiation. In one application, PhCs are composed of a number of dielectric rods that can be arranged to make an accelerator cavity. These structures trap an accelerating mode and allow higher order modes to propagate out. Previous work showed that PhC structures allow excitation of unwanted transverse wake-fields that can disrupt the beam and limit luminosity levels. This work focuses on optimizing PhC cavities to reduce transverse wake-fields by minimizing the Q-factor of unwanted modes, while keeping the Q-factor of the accelerating mode high. The transverse wake-fields in the new optimized structures are compared with previously optimized structures and the CLIC cavity with HOM damping. [Preview Abstract] |
Sunday, April 14, 2013 10:06AM - 10:18AM |
G15.00009: A superradiant Raman laser as an atomic sensor Justin G. Bohnet, Zilong Chen, Joshua M. Weiner, Kevin C. Cox, James K. Thompson We have realized an atomic sensor that combines active, wideband sensing with passive measurement periods using dynamic control of a cold-atom, superradiant Raman laser. Superradiant lasers have been proposed as highly stable optical frequency references for next generation precision measurement experiments. Collective emission of the atomic gain medium maps the quantum phase of the atomic ensemble onto the detected cavity field. This quantum phase can also be sensitive to the environment, allowing the laser to function as a sensor in addition to a frequency reference. We discuss the fundamental precision of the superradiant mapping and show that the non-demolition measurement can theoretically approach the standard quantum limit on phase estimation for a coherent spin state. Finally, we present experimental demonstrations of a superradiant Raman laser operated as a hybrid active/passive atomic measurement device. [Preview Abstract] |
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