H. Ao

Transverse Tuning Scheme for J-PARC Linac

A transverse matching scheme has been planned for the J-PARC linac beam commissioning with use of wire scanners. The beam diagnosis layout has been determined to realize the planned matching scheme. Continuous monitoring of the matching with beam position monitors is also discussed.

Fabrication status of acs accelerating modules of J-PARC LINAC

We have been fabricated the several ACS modules step by step: the first buncher, the second buncher, the low-beta accelerating module, and so on. This paper reports the improvement of the frequency and summarizes these RF measurement results. The data of the frequency fluctuation from brazing or stacking have been accumulated, and then the second buncher could be tuned correctly, although the frequency of the first buncher was lower than the target design. In the present fabrication process, about 0.1 to 0.2 MHz fluctuation should be corrected at each measurement step. As the result, the frequency could be tuned to the range of the movable tuner.

Comparison of trajectory between modelling and experiment for J-PARC linac

In the beam commissioning of J-PARC (Japan Proton Accelerator Research Complex) linac, three simulations codes are used to model the accelerator. We have compared the modeling with the experimental results obtained in the beam commissioning to date, where a basic agreement has been confirmed between the modeling and the actual beam behavior.

High power conditioning of the DTL for J-PARC

The high-power conditioning of the three DTL tanks for the J-PARC has been started in October 2006. The design rf peak-power levels for beam acceleration of the tanks are about 1.1 MW (DTL1), 1.2 MW (DTL2) and 1.0 MW (DTL3), respectively. As a result of the conditioning, we have achieved that the rf power levels are about 1.3 MW, 1.45 MW and 1.23 MW of which are 1.2 times the power levels of the desired one (the pulse length is 650 mus and the pulse repetition is 25 Hz). During the linac beam commissioning, the DTLs can keep the required rf power stable now.

An Alignment of J-PARC Linac

J-PARC linear accelerator components are now being installed in the accelerator tunnel, whose total length is more than 400 m including the beam transport line to 3GeV synchrotron. A precise alignment of accelerator components is essential for high quality beam acceleration. In this paper, planned alignment schemes for the installation of linac components and watching the long term motion of the building are described. Markings are placed on the floor, which act as a reference for the initial alignment at the installation. For a straight line alignment, the wire position sensor is placed on the offset position with respect to the beam center by a target holder. The hydrostatic levering system is used for watching the floor elevation over the long period.

Cold-model tests of an annular coupled structure for upgrade of a J-PARC linac

An annular coupled structure (ACS) has been developed for upgrade of a J-PARC (Japan Proton Accelerator Research Complex) linac from 180 MeV to 400 MeV. Although install area is prepared for the ACS cavities at an initial construction, it will be used as a beam-transport line temporarily. Aluminum and copper models were fabricated for RF properties confirmation based on an initial design, and for final optimization. RF measurement procedure of the ACS structure was also studied thorough the R&D process. Many items should be considered for mass production; schedule, handling parts, utilities, and so on. The measurement results of models and some fabrication status are presented.

Rf Tuning and Fabrication Status of the First Module for J-PARC ACS

J-PARC Linac starts with 180-MeV SDTL temporary, and it is upgraded to 400-MeV with 21 ACS (Annular Coupled Structure) modules and two ACS bunchers and two debunchers [1]. First buncher module is under fabrication, and second buncher and a few accelerating modules are also planed until FY2006. The first ACS module consists of two 5-cells ACS tanks and a 5-cells bridge cavity for the buncher module. Three RF tuners are installed to the bridge cavity for fine RF tuning. An operating frequency should be tuned to 972 MHz within the fine-tuning range before a brazing process in a factory. The tuning procedure has been studied with RF simulation analysis and cold-model measurements for ACS and bridge cells [2]. This paper describes RF tuning results, fabrication status and related development items.

FRIB Project Status and Beam Instrumentation Challenges

With an average beam power two orders of magnitude higher than operating heavy-ion facilities, the Facility for Rare Isotope Beams (FRIB) stands at the power frontier of the accelerator family. This paper summarizes the status of design, technology development, construction, commissioning, as well as path to operations and upgrades. We highlight beam instrumentation challenges including machine protection of high-power heavy-ion beams and complications of multi-charge-state and multi-ion-species accelerations.

The FRIB Superconducting Linac - Status and Plans

With an average beam power two orders of magnitude higher than operating heavy-ion facilities, the Facility for Rare Isotope Beams (FRIB) stands at the power frontier of the accelerator family. This report summarizes the current design and construction status as well as plans for commissioning, operations, and upgrades.

Design of a FRIB Half-Wave Pre-Production Cryomodule

The driver linac for the Facility for Rare Isotope Beams (FRIB) will require the production of 48 cryomodules (CMs). In addition to the =0.085 quarter-wave CM, FRIB has completed the design of a =0.53 half-wave CM as a pre-production prototype. This CM will qualify the performance of the resonators, fundamental power couplers, tuners, and cryogenic systems of the =0.53 half-wave design. In addition to the successful systems qualification; the =0.53 CM build will also verify the FRIB bottom up assembly and alignment method on a half-wave CM type. The lessons learned from the =0.085 pre-production CM build including valuable fabrication, sourcing, and assembly experience have been applied to the design of =0.53 half-wave CM. This paper will report the design of the =0.53 half-wave CM as well as the CM interfaces within the linac tunnel.