Engineering topics
Bertsche, Kirk J
Publications and source records attributed to Bertsche, Kirk J.
Parameters for the PEP-II B-Factory at SLAC in 2008
The PEP-II B-Factory at SLAC (3.1 GeV e{sup +} x 9.0 GeV e{sup -}) operated from 1999 to 2008, delivering luminosity to the BaBar experiment. The design luminosity was reached after one and a half years of operation. In the end PEP-II surpassed, by four times, its design luminosity reaching 1.21 x 10{sup 34} cm{sup -2}s{sup -1}. It also set world stored beam current records of 2.1 A e{sup -} and 3.2 A e{sup +}. Continuous injection was implemented with BaBar successfully taking data. The total delivered luminosity to the BaBar detector was 557.4 fb{sup -1} spanning five upsilon resonances. PEP-II was constructed by SLAC, LBNL, and LLNL with help from BINP, IHEP, the BaBar collaboration, and the US DOE OHEP.
High-Current Effects in the PEP-II Storage Ring
The PEP-II B-Factory operated at peak and integrated luminosity several times the original design values. Its storage rings operated at world-record beam currents with bunch lengths of about 10 mm. Correspondingly significant heat load was imposed on the vacuum system, both due to synchrotron radiation and by energy loss into higher-order modes. The latter in turn would lead to local heating or discharges wherever such energy got absorbed. Over the course of PEP-II running we experienced numerous such effects, which lead to upgrade programs of significant scope. In the following we will describe the most significant of such effects and their mitigation: (1) Upgrades and repairs of RF seals and shields in both rings; (2) Redesign of overheating stripline kicker electrodes to withstand higher powers; and (3) Redesign and replacement of BPM buttons following failure.
Ideas for a Future PEP-X Light Source
SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing synchrotron source -- PEP-X -- a new storage ring that would occupy the existing PEP-II tunnel and support two experimental halls, each containing 16 x-ray beam lines. Operating at 4.5 GeV and 1.5 A with a horizontal emittance of 0.14 nm-rad, reached using 90 m of damping wigglers, PEP-X would have an order of magnitude higher average brightness and flux in the 1-{angstrom} x-ray range than any existing or planned future storage ring sources. Higher brightness in the soft x-ray regime might be reached with partial lasing in long undulators, and high peak brightness could be reached with seeded FEL emission. The status of preliminary studies of PEP-X is presented.
Design of a 10**36 CM-2 S-1 Super-B Factory
Parameters have been studied for a high luminosity e{sup +}e{sup -} collider operating at the Upsilon 4S that would deliver a luminosity of 1 to 4 x 10{sup 36}/cm{sup 2}/s. This collider, called a Super-B Factory, would use a combination of linear collider and storage ring techniques. In this scheme an electron beam and a positron beam are stored in low-emittance damping rings similar to those designed for a Linear Collider (LC) or the next generation light source. A LC style interaction region is included in the ring to produce sub-millimeter vertical beta functions at the collision point. A large crossing angle (+/- 24 mrad) is used at the collision point to allow beam separation. A crab-waist scheme is used to reduce the hourglass effect and restore peak luminosity. Beam currents of 1.8 A at 4 x 7 GeV in 1251 bunches can produce a luminosity of 10{sup 36}/cm{sup 2}/s with upgrade possibilities. Such a collider would produce an integrated luminosity of about 10,000 fb{sup -1} (10 ab{sup -1}) in a running year (10{sup 7} sec) at the {gamma}(4S) resonance. Further possibilities include having longitudinally polarized e- at the IR and operating at the J/Psi and Psi beam energies.