A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z    

Wang, D.

Paper Title Page
TPPP017 Beam-Beam Effects in the Ring-Ring Version of eRHIC 1520
 
  • J. Shi, L. Jin
    KU, Lawrence, Kansas
  • D. Wang, F. Wang
    MIT, Middleton, Massachusetts
 
  Funding: The U.S. Department of Energy under Grant No. DE-FG02-04ER41288.

The eRHIC is a proposed electron ring at the RHIC that will provide collisions between a polarized 5-10 GeV electron beam and an ion beam from one of the RHIC rings. In order to achieve proposed high luminosity, large bunch current and small beta-functions at the IP has to be employed. Such measures result in large beam-beam parameters, 0.029 and 0.08 for the electron beam and 0.0065 and 0.0033 for the proton beam in the horizontal and vertical plane, respectively, in the current ZDR design. The beam-beam effect especially the coherent beam-beam effect is therefore one of important issues to the eRHIC. Moreover, the proposed configuration of unequal circumferences of the electron and proton rings could further enhance the coherent beam-beam effect. The beam-beam effect of eRHIC has therefore been studied with a self-consistent beam-beam simulation by using the particle-in-cell method. Beam-beam limits of the electron and proton beam were examined as thresholds of the onset of coherent beam-beam instability. For the proposed luminosity, the electron and proton bunch currents optimized with the consideration of the beam-beam effect will be discussed.

 
TPPP019 Collective Effects in Lepton Ring of eRHIC 1628
 
  • D. Wang, M. Farkhondeh, C. Tschalaer, F. Wang, A. Zolfaghari, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
  • M. Blaskiewicz, Y. Luo, L. Wang
    BNL, Upton, Long Island, New York
 
  Funding: Department of Energy.

The eRHIC is a new generation lepton-hadron collider undergoing design studies by a collaboration of BNL, MIT, DESY and BINP. The collider complex will consist of a hadron machine that is mainly the existing RHIC with necessary upgrades, and a new lepton machine that can provide intense, highly polarized electron and positron beams at energy of 5-10 GeV. The ring-ring option of eRHIC is to build a 5-10 GeV electron ring with a injector chain. In this paper the beam lifetime of lepton beams is calculated.

 
TPPP045 Interaction Region Design for the Electron-Ion Collider eRHIC 2893
 
  • C. Montag, B. Parker, S. Tepikian
    BNL, Upton, Long Island, New York
  • D. Wang
    MIT, Middleton, Massachusetts
 
  Funding: Work performed under the auspices of the U.S. Department of Energy.

To facilitate the study of collisions between 10 GeV polarized electrons and 100 GeV/u heavy ions or 250 GeV polarized protons at high luminosities, adding a 10 GeV electron storage ring to the existing RHIC complex has been proposed. The interaction region of this electron-ion collider eRHIC has to provide the required low-beta focusing, while simultaneously accomodating the synchrotron radiation fan generated by beam separation close to the interaction point, which is particularly challenging. The latest design status of the eRHIC interaction region is presented.

 
TPPT095 Test of a Fast Ferrite Reactive Tuner for Control of Microphonics at the S-Dalinac
 
  • T. Zwart, dc. Cheever, N.T. Cliffer, M. Farkhondeh, W. Graves, W. North, C. Tschalaer, D. Wang, D. Wang, F. Wang, A. Zolfaghari, J. van der Laan
    MIT, Middleton, Massachusetts
  • H.-D. Gräf
    TU Darmstadt, Darmstadt
 
  Funding: DOE

A fast ferrite inductive tuner assembly has been constructed for use at the 3 GHz superconducting S-Dalinac accelerator. This device was installed and tested at the S-Dalinac in April 2005. At a fixed accelerating field of 1.4 MV/m using a simple analog control loop the amplitude of the cavity peak-to-peak phase fluctuations with respect to the phase of the incident RF was reduced from 80 degrees to 10 degrees. The 50 Hz noise which dominated the open loop microphonics was reduced by more than 30 dB. The open loop response of the reactive tuner has also been characterized, yielding a tuning range of ?f greater than 300 Hz at a Qext of 1.5e7. The ferrite tuner was then relocated on the waveguide to a distance of (n+1/4)? from the input coupler. This allowed fast control of the coupling with range of Qext from 1.5 - 8e7.

 
TPPT095 Test of a Fast Ferrite Reactive Tuner for Control of Microphonics at the S-Dalinac
 
  • T. Zwart, dc. Cheever, N.T. Cliffer, M. Farkhondeh, W. Graves, W. North, C. Tschalaer, D. Wang, D. Wang, F. Wang, A. Zolfaghari, J. van der Laan
    MIT, Middleton, Massachusetts
  • H.-D. Gräf
    TU Darmstadt, Darmstadt
 
  Funding: DOE

A fast ferrite inductive tuner assembly has been constructed for use at the 3 GHz superconducting S-Dalinac accelerator. This device was installed and tested at the S-Dalinac in April 2005. At a fixed accelerating field of 1.4 MV/m using a simple analog control loop the amplitude of the cavity peak-to-peak phase fluctuations with respect to the phase of the incident RF was reduced from 80 degrees to 10 degrees. The 50 Hz noise which dominated the open loop microphonics was reduced by more than 30 dB. The open loop response of the reactive tuner has also been characterized, yielding a tuning range of ?f greater than 300 Hz at a Qext of 1.5e7. The ferrite tuner was then relocated on the waveguide to a distance of (n+1/4)? from the input coupler. This allowed fast control of the coupling with range of Qext from 1.5 - 8e7.

 
RPAE068 Very Short Bunches in MIT-Bates South Hall Ring 3768
 
  • D. Wang, dc. Cheever, M. Farkhondeh, W.A. Franklin, W. Graves, E. Ihloff, C. Tschalaer, D. Wang, D. Wang, F. Wang, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
  • B. Podobedov
    BNL, Upton, Long Island, New York
 
  Funding: Department of Energy

The study of ultra-short bunches in MIT SHR storage ring with very small momentum compactions is carried out. The ultra-short bunches are to greatly enhence the coherent radiation by many orders of magnitude. The ring lattice is resigned to reach very small momentum compaction factor down to 1·10-5 levels. The measurement is performed with the streak camera. The various associated issues are discussed.

 
RPAE068 Very Short Bunches in MIT-Bates South Hall Ring 3768
 
  • D. Wang, dc. Cheever, M. Farkhondeh, W.A. Franklin, W. Graves, E. Ihloff, C. Tschalaer, D. Wang, D. Wang, F. Wang, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
  • B. Podobedov
    BNL, Upton, Long Island, New York
 
  Funding: Department of Energy

The study of ultra-short bunches in MIT SHR storage ring with very small momentum compactions is carried out. The ultra-short bunches are to greatly enhence the coherent radiation by many orders of magnitude. The ring lattice is resigned to reach very small momentum compaction factor down to 1·10-5 levels. The measurement is performed with the streak camera. The various associated issues are discussed.

 
RPAE068 Very Short Bunches in MIT-Bates South Hall Ring 3768
 
  • D. Wang, dc. Cheever, M. Farkhondeh, W.A. Franklin, W. Graves, E. Ihloff, C. Tschalaer, D. Wang, D. Wang, F. Wang, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
  • B. Podobedov
    BNL, Upton, Long Island, New York
 
  Funding: Department of Energy

The study of ultra-short bunches in MIT SHR storage ring with very small momentum compactions is carried out. The ultra-short bunches are to greatly enhence the coherent radiation by many orders of magnitude. The ring lattice is resigned to reach very small momentum compaction factor down to 1·10-5 levels. The measurement is performed with the streak camera. The various associated issues are discussed.

 
TPPP022 The eRHIC Ring-Ring Collider Design 1766
 
  • F. Wang, M. Farkhondeh, W.A. Franklin, W. Graves, R. Milner, C. Tschalaer, D. Wang, A. Zolfaghari, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
  • D.P. Barber
    DESY, Hamburg
  • J. Beebe-Wang, A. Deshpande, V. Litvinenko, W.W. MacKay, C. Montag, S. Ozaki, B. Parker, S. Peggs, V. Ptitsyn, T. Roser, S. Tepikian, D. Trbojevic
    BNL, Upton, Long Island, New York
 
  The eRHIC ring-ring collider is the main design option of the future lepton-ion collider at Brookhaven National Laboratory. We report the revisions of the ring-ring collider design features to the baseline design presented in the eRHIC Zeroth Design Report (ZDR). These revisions have been made during the past year. They include changes of the interaction region which are required from the modifications in the design of the main detector. They also include changes in the lepton storage ring for high current operations as a result of better understandings of beam-beam interaction effects. The updated collider luminosity and beam parameters also take into account a more accurate picture of current and future operational aspects of RHIC.  
RPAE069 Terahertz Coherent Synchrotron Radiation in the MIT-Bates South Hall Ring 3783
 
  • F. Wang, dc. Cheever, M. Farkhondeh, W.A. Franklin, W. Graves, E. Ihloff, C. Tschalaer, D. Wang, D. Wang, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
  • G.L. Carr, B. Podobedov
    BNL, Upton, Long Island, New York
  • F. Sannibale
    LBNL, Berkeley, California
 
  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. Beam dynamics issues related to short bunch length operation, and may associated with the high frequency RF system, such as multi-bunch instability are concerned. They could affect bunch length, bunch intensity and beam stability. The SHR is ideal for experimental exploration of these problems. Results of initial test of low momentum compaction lattice and bunch length measurements are presented and compared to expectations.  
RPAE069 Terahertz Coherent Synchrotron Radiation in the MIT-Bates South Hall Ring 3783
 
  • F. Wang, dc. Cheever, M. Farkhondeh, W.A. Franklin, W. Graves, E. Ihloff, C. Tschalaer, D. Wang, D. Wang, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
  • G.L. Carr, B. Podobedov
    BNL, Upton, Long Island, New York
  • F. Sannibale
    LBNL, Berkeley, California
 
  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. Beam dynamics issues related to short bunch length operation, and may associated with the high frequency RF system, such as multi-bunch instability are concerned. They could affect bunch length, bunch intensity and beam stability. The SHR is ideal for experimental exploration of these problems. Results of initial test of low momentum compaction lattice and bunch length measurements are presented and compared to expectations.  
RPPT027 Considerations on Beam Quality Control in MIT X-Ray FEL 1961
 
  • D. Wang, W. Graves, D. Wang, T. Zwart
    MIT, Middleton, Massachusetts
  • P. Emma, J. Wu
    SLAC, Menlo Park, California
  • G. Huang
    LBNL, Berkeley, California
 
  Funding: U.S. Department of Energy.

The next generation of x-ray FEL requires very high quality electron beams for producing unprecedented x-ray radiations. In proposed x-ray FEL facilities, especially those that use multi-stage high gain high harmonic (HGHG) principle to obtain coherence in both transverse and longitudinal dimensions, the arrival timing of electron bunches must be very precise to ensure the seed laser overlap the desired sections of the electron bunch. A scheme is proposed to achieve 10s fs level of arrival timing control level.

 
RPPT027 Considerations on Beam Quality Control in MIT X-Ray FEL 1961
 
  • D. Wang, W. Graves, D. Wang, T. Zwart
    MIT, Middleton, Massachusetts
  • P. Emma, J. Wu
    SLAC, Menlo Park, California
  • G. Huang
    LBNL, Berkeley, California
 
  Funding: U.S. Department of Energy.

The next generation of x-ray FEL requires very high quality electron beams for producing unprecedented x-ray radiations. In proposed x-ray FEL facilities, especially those that use multi-stage high gain high harmonic (HGHG) principle to obtain coherence in both transverse and longitudinal dimensions, the arrival timing of electron bunches must be very precise to ensure the seed laser overlap the desired sections of the electron bunch. A scheme is proposed to achieve 10s fs level of arrival timing control level.

 
FPAE031 Polarized Electron Beams for Nuclear Physics at the MIT Bates Accelerator Center
 
  • M. Farkhondeh, dc. Cheever, W.A. Franklin, E. Ihloff, B. McAllister, R. Milner, W. North, C. Tschalaer, E. Tsentalovich, D. Wang, D. Wang, F. Wang, A. Zolfaghari, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
 
  Funding: U.S. Department of Energy.

The MIT Bates Accelerator Center is delivering highly polarized electron beams to its South Hall Ring for use in Nuclear Physics Experiments. Circulating electron currents in excess of 200 mA with polarization of 70% are scattered from a highly polarized, but very thin atomic beam source deuterium target. At the electron source a compact diode laser creates photoemission of quasi-CW mA pulses of polarized electrons at low duty factors from a strained GaAs photocathode. Refurbished RF transmitters provide power to the 2856 MHz linac, accelerating the beam to 850 MeV in two passes before injection into the South Hall Ring. In the ring a Siberian snake serves to maintain a high degree of longitudinal polarization at the BLAST scattering target. A Compton laser back-scattering polarimeter measures the electron beam polarization with a statistical acuracy of 6% every 15 minutes.

 
FPAE031 Polarized Electron Beams for Nuclear Physics at the MIT Bates Accelerator Center
 
  • M. Farkhondeh, dc. Cheever, W.A. Franklin, E. Ihloff, B. McAllister, R. Milner, W. North, C. Tschalaer, E. Tsentalovich, D. Wang, D. Wang, F. Wang, A. Zolfaghari, T. Zwart, J. van der Laan
    MIT, Middleton, Massachusetts
 
  Funding: U.S. Department of Energy.

The MIT Bates Accelerator Center is delivering highly polarized electron beams to its South Hall Ring for use in Nuclear Physics Experiments. Circulating electron currents in excess of 200 mA with polarization of 70% are scattered from a highly polarized, but very thin atomic beam source deuterium target. At the electron source a compact diode laser creates photoemission of quasi-CW mA pulses of polarized electrons at low duty factors from a strained GaAs photocathode. Refurbished RF transmitters provide power to the 2856 MHz linac, accelerating the beam to 850 MeV in two passes before injection into the South Hall Ring. In the ring a Siberian snake serves to maintain a high degree of longitudinal polarization at the BLAST scattering target. A Compton laser back-scattering polarimeter measures the electron beam polarization with a statistical acuracy of 6% every 15 minutes.