115079519
CONSTRUCTION OF THE S1-GLOBAL CRYOMODULES FOR ILC
In an attempt to demonstrate an average accelerating gradient of 31.5 MV/m as in the design of the ILC, the S1-Global project [1] is a cryomodule being constructed by an international collaboration hosted by KEK and including INFN, FNAL, DESY and SLAC. The S1Global system joins two half-length cryomodules, each 6 m in length and containing 4 cavities, Module-C contains cavities from FNAL and DESY and was constructed by INFN. Module-A contains four KEK cavities and was constructed by KEK. The assembly of the cryomodules started in January 2010, and was just completed in May. In this paper, construction experience of the S1-Global cryomodule is presented. INTRODUCTION The S1-Global cryomodule was proposed and approved as an international collaborative effort at the SCRF meeting of the ILC Global Design Effort in April 2008. The goals of the S1 Global program are to attempt to achieve an average accelerating gradient of 31.5MV/m across 8 cavities. To accomplish this, eight cavities and couplers are contributed from FNAL, DESY and KEK, and installed in two ‘half cryomodules’ each 6 m long: Module-C, a new cryomodule designed and constructed by INFN; and Module-A, a modified STF cryomodule by KEK. The S1-G cryomodule design work was completed in January 2009, and the assembly started in January 2010. The collaborative framework of S1-G is demonstrated in the contributions of the participating laboratories: INFN: Design and construction Module-C and production of the blade tuners for the FNAL cavities. FNAL: Two TESLA type cavities [2], power couplers and integration of the INFN blade tuners in the cavity packages. DESY: Two TESLA type cavities, including Saclaytype tuners, and power couplers. SLAC: Power distribution for Module-C, and aging of FNAL couplers. KEK: Four TESLA-like cavities, with two types of tuner design, Module-A for KEK cavities [3], power distribution for Module-A, and infrastructure for tests. DESIGN OF S1-GLOBAL CRYOMODULE The S1-Global assembly is shown in Fig. 1. Two cavities from FNAL and two form DESY are installed in the Module-C, and four cavities of two types by KEK are installed in Module-A. The total length of the S1-Global assembly is 14.9 m. The parameters of the two cryomodules are listed in Table 1. The cross section of Module-C has the same design as the TTF-type III cryomodule [4]. The cold mass is supported to the vacuum vessel by two composite cylindrical posts spaced 3200 mm apart. All four input couplers are separated by a distance of 1384.15 mm at room temperature. The designs of FNAL and DESY cavity packages differ because of the tuner types, the Blade tuner and the Saclay-type tuner. The difference in length is made up in the bellows between packages. Fig.1: S1-G cryomodule and cavity package of each laboratory. (a): FNAL cavity with Blade tuner, (b): DESY cavity with Saclay-type tuner, (c): KEK-a cavity with slide jack tuner and (d) KEK-b cavity. WEPE008 Proceedings of IPAC’10, Kyoto, Japan 3356 03 Linear Colliders, Lepton Accelerators and New Acceleration Techniques A03 Linear Colliders Table 1: S1-Global Cryomodule Parameters
122318830
Cryomodule tests of four Tesla-like cavities in the Superconducting RF Test Facility at KEK
A 6-m cryomodule including four Tesla-like cavities was developed, and was tested in the Superconducting RF Test Facility phase-I at KEK. The performance as a total superconducting cavity system was checked in the cryomodule tests at 2 K with high rf power. One of the four cavities achieved a stable pulsed operation at $32\text{ }\text{ }\mathrm{MV}/\mathrm{m}$, which is higher than the operating accelerating gradient in the ILC. The maximum accelerating gradient (${E}_{\mathrm{acc},\mathrm{max}﻿}$) obtained in the vertical cw tests was maintained or slightly improved in the cryomodule tests operating in a pulse mode. Compensation of the Lorentz force detuning at $31\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ was successfully demonstrated by a piezo tuner and predetuning.
67849446
PREPARATION STATUS OF CRYOMODULE TESTS OF TESLA-LIKE CAVITIES IN S1-GLOBAL PROJECT AT KEK
S1-Global project for ILC is an international collaboration for cryomodule tests including eight 9-cell sc cavities from DESY, FNAL and KEK. One of two 6-m cryomodules, Cryomodule-A, contains four Tesla-like cavities with slide-jack tuners and STF-II couplers. The cryomodule was assembled and was installed in the STF tunnel for cool-down tests and high power rf tests. The current preparation status is reported.
113679678
PRESENT STATUS OF SUPERCONDUCTING CAVITY SYSTEM FOR CERL INJECTOR LINAC AT KEK
Construction of the compact ERL (cERL) [1] is underway and fabrication of a SC Cavity Injector Cryomodule has been started last year at KEK. Status of R&D and design details are reported.
118396635
Slow-roll Inflation with the Gauss-Bonnet and Chern-Simons Corrections
We study slow-roll inflation with the Gauss-Bonnet and Chern-Simons corrections. We obtain general formulas for the observables: spectral indices, tensor-to-scalar ratio and circular polarization of gravitational waves. The Gauss-Bonnet term violates the consistency relation r = −8nT. Particularly, blue spectrum nT > 0 and scale invariant spectrum |8nT|/r << 1 of tensor modes are possible. These cases require the Gauss-Bonnet coupling function of ξ, ~ 108/MPl. We use examples to show new-inflation-type potential with 10MPl symmetry breaking scale and potential with flat region in 10MPl lead to observationally consistent blue and scale invariant spectra, respectively. Hence, these interesting cases can actually be realized. The Chern-Simons term produce circularly polarized tensor modes. We show an observation of these signals supports existence of the Chern-Simons coupling function of ω, ~ 108/MPl. Thus, with future observations, we can fix or constrain the value of these coupling functions, at the CMB scale.