Abstracts Brochure - CERN

TUPLS — Poster Session 27-Jun-06 16:00 - 18:00
Design of the LHC Beam Dump Entrance Window
TeV proton beams from the LHC are ejected
through a 600 m long beam dump transfer R. Veness, B. Goddard, S.J. Mathot, A. Presland (CERN)
line vacuum chamber to a beam dump block.
The dump block is contained within an inert gas-filled vessel to prevent a possible fire risk. The dump vessel and
transfer line are separated by a 600 mm diameter window, which must withstand both the static pressure load and
thermal shock from the passage of the LHC beam. In a previous paper* the functional requirements and conceptual
design of this window were outlined. This paper describes the analysis leading to the final design of the window.
The choice of materials is explained and tests performed on the prototype window are summarized.
*A. Presland et al. "A large diameter entrance window for the LHC beam dump line". Proc. PAC 2005, 1698-1700.
An RF Chopper for the Rare Isotope Accelerator
We present the study for the design of a radiofrequency
chopper to be installed on the S. De Santis, J.M. Byrd, R. Keller, A. Ratti (LBNL) F. Caspers (CERN)
Rare Isotope Accelerator (RIA). The RIA facility
is a research accelerator for the production of unstable isotope, supplying 400 kW beams to four different
experimental areas. The radiofrequency chopper is an essential component for providing individual intensity adjustment
to the beams, by selectively switching beam out of the RFQ onto a high-power stopping target. We investigated
the use of a meander line structure, scaled from the CERN SPL design, able to provide the necessary deflection for
a wide range of ions up to U+28. The repetition rate is fixed to 28.75 MHz, equal to half the RFQ frequency, which
allows for chopping every second bunch. Computer simulations with Microwave Studio were performed to optimize
the meander line design and we analyzed the use of a double sine wave generator for the 1.4 kV pulser, which greatly
limits the power dissipation. Our design is characterized by good coverage factor and field resolution along the beam
direction; easy fabrication, radiation hardness and good power handling capabilities.
Spin Transport from AGS to RHIC with Two Partial Snakes in AGS
The stable spin direction in the RHIC rings
is vertical. With one or two strong helical W.W. MacKay, A.U. Luccio, N. Tsoupas (BNL)
Siberian snakes in the AGS, the stable spin
direction at extraction is not vertical. Interleaved vertical and horizontal bends in the transport line between AGS
and the RHIC rings also tend to tip the spin away from the vertical. In order to preserve polarization in RHIC, we
examine several options to improve the matching of the stable spin direction during beam transfer from the AGS to
each of the RHIC rings. While the matching is not perfect, the most economical method appears to be a lowering of
the injection energy by one unit of G*gamma to 45.5.
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