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Nosochkov, Y.

Paper Title Page
MOPP046 Collimation Optimizations, Capture Efficiency, and Primary-Beam Power Loss in the ILC Positron Source 649
 
  • F. Zhou, Y. Nosochkov, J. Sheppard
    SLAC, Menlo Park, California
  • W. Liu
    ANL, Argonne, Illinois
 
  The ILC positron beam generated from a thin Ti target has a wide energy spread and large transverse divergence. With the collection optics immediately downstream of the target and pre-acceleration to 125 MeV, the collected positron beam still has a long tail of positrons with low energies and large transverse divergence, which will be lost in the rest of the ILC positron source beamline. A collimation system is proposed and optimized for the case of a shielded target with quarter-wave transformation collection optics so that the power loss in the magnets and RF structures is effectively controlled within the acceptable level and in the damping ring (DR) within 640 W, assuming 3× 1010 of the captured positrons per bunch in the DR. In this case, the capture efficiency and DR injection efficiency are 13% and 99.8%, respectively. The lower capture efficiency is expected to result in higher injection efficiency and therefore, a lower power loss in the DR. The capture efficiency for the cases of a shielded target with flux concentrator and 5-T immersed target with flux concentrator is 20% and 30%, respectively, with the collimation system.  
WEPC059 Lattice Design of PEP-X as a Light Source Machineat SLAC 2127
 
  • M.-H. Wang, Y. Cai, R. O. Hettel, Y. Nosochkov
    SLAC, Menlo Park, California
 
  The lattice study for converting the High Energy Ring (HER) of PEP-II into a light source machine with minimal modifications is reported. In this design, a higher phase advance is used in the HER FODO lattice which reduces the emittance to 5 nm at 4.5 GeV without a damping wiggler, and to 0.4 nm with 116 m damping wiggler included in two straight sections out of six. We also study the possibility of replacing one of the six FODO arcs with eight DBA cells to provide additional dispersion free straight sections for the experimental beam lines. The DBA cells will reuse the existing HER and LER (Low Energy Ring) magnets for a minimal cost of the modification. The main parameters and beam dynamics properties of these lattices are presented.  
WEPP044 Commissioning the 90° Lattice for the PEP II High Energy Ring 2617
 
  • W. Wittmer, Y. Cai, W. X. Cheng, W. S. Colocho, F.-J. Decker, S. Ecklund, A. S. Fisher, Y. Nosochkov, A. Novokhatski, M. K. Sullivan, U. Wienands, Y. T. Yan, G. Yocky
    SLAC, Menlo Park, California
 
  In order to benefit from further reduction of the vertical IP beta function of the PEP-II HER the bunch length should be reduced. This will be achieved by changing the phase advance from 60 deg to 90 deg in the four arcs not adjacent to the IR region, thus reducing momentum compaction by about 30% and reducing bunch length from a present 12 mm down to 8.5 mm at low beam current. In preparation to implement the 90 deg lattice the main HER quadrupole and sextupole strings and their power supplies have been reconfigured. Compared to the 60 deg lattice it was expected that dynamic aperture and injection will be more difficult. The synchrotron tune initially will be lower but can be brought back by raising the rf voltage. Beam emittance is held at 48 nmr by introducing a significant dispersion beat in the arcs. The lattice was successfully commissioned at currents up to 800mA in August 2007. In this paper we will compare the actual machine with the predicted behaviour, explain the correction strategies used and give an overall assessment of the operation and the benefit of the new lattice configuration.  
WEPP164 Beam Collimation Studies for the ILC Positron Source 2871
 
  • A. I. Drozhdin
    Fermilab, Batavia, Illinois
  • Y. Nosochkov, F. Zhou
    SLAC, Menlo Park, California
 
  The results of collimation studies for the ILC positron source beam line are presented. The calculations of primary positron beam loss are done using the ELEGANT code. The secondary positron and electron beam loss, synchrotron radiation along the beam line and bremsstrahlung radiation in the collimators are simulated using the STRUCT code. The first part of the system, located right after the positron source target at 0.125 GeV, is used for protection of super-conducting RF Linac from heating and radiation. The second part of the system is used for final collimation of the beam before injection to the Damping Ring at 5 GeV. The calculated power loss in the collimation region is about 100 W/m, with loss in the collimators of 0.2-5 kW. The beam transfer efficiency from target to the Damping Ring is 13.5%.  
WEPC023 Ideas for a Future PEP Light Source 2031
 
  • R. O. Hettel, K. L.F. Bane, L. D. Bentson, K. J. Bertsche, S. M. Brennan, Y. Cai, A. Chao, S. DeBarger, V. A. Dolgashev, X. Huang, Z. Huang, D. Kharakh, Y. Nosochkov, T. Rabedeau, J. A. Safranek, J. Seeman, J. Stohr, G. V. Stupakov, S. G. Tantawi, L. Wang, M.-H. Wang, U. Wienands
    SLAC, Menlo Park, California
  • I. Lindau
    Stanford University, Stanford, Califormia
  • C. Pellegrini
    UCLA, Los Angeles, California
 
  With the termination of operation of the PEP-II storage rings for high energy physics at hand, and with the migration of accelerator operation at SLAC in general to photon science applications, a study of the potential conversion of the PEP-II to a future light source has been initiated. With a circumference of 2.2 km and the capability for high current operation, it is clear that operating a converted ring at medium energy (3-6 GeV) could offer very low emittance and an average brightness of order 1022, limited primarily by the power handling capacity of photon beam line optical components. Higher brightness in the soft X-ray regime might be reached with partial lasing in long undulators if the emittance is sufficiently low, and high peak brightness could be reached with seeded FEL emission. Advanced pulsed rf technology might be used to generate short bunches and fast switched polarization in soft X-ray rf undulators. An overview of the preliminary findings of the PEP Light Source study group will be presented, including lattice, X-ray source and beam line options.