TRIUMF, Vancouver
The ISAC-II superconducting heavy ion linac now accelerates radioactive ion beams with the highest gradient of any operating SC ion facility in the world and provides a 20 MV boost to the ISAC accelerated beams. The addition of a further 20 MV of SC linac, with cavities made in Canada, will be installed by the end of 2009. The ISAC-III project scheduled to begin in 2010 will see the installation of an additional driver beam of 50 MeV electrons to produce RIBs by photofission, an expanded target area, and new front-end ion accelerators to expand the capability to three simultaneous radioactive beams for experiments.
TRIUMF, Vancouver
The ISAC-III proposal is a ten year plan to triple the amount of radioactive ion beam (RIB) time at the facility. The plan includes the addition of two new independent target stations with a design suitable for actinide target materials, a second 500 MeV proton beam line from the TRIUMF cyclotron and a new 50 MeV electron linac as a complementary driver to provide RIBs through photo-fission. The two new target stations will require a new mass-separator and low-energy beam-transport complex to deliver the additional beams to the ISAC experimental facilities. It is also proposed to install a new linear accelerator section to provide the capability for two simultaneous accelerated RIBs to experimenters. This paper will describe the proposed installations in the low-energy transport and accelerator sections of the ISAC complex.
TRIUMF, Vancouver
The ISAC-II superconducting linac, operational since April 2006, adds 20 MV accelerating potential to the ISAC Radioactive Ion Beam (RIB) facility. An upgrade to the linac, in progress, calls for the addition of a further 20 MV of accelerating structure by the end of 2009. The new installation consists of twenty 141 MHz quarter wave cavities at a design beta of 11%. The cavities will be housed in three cryomodules with six cavities in the first two cryomodules and eight cavities in the last. A second Linde TC50 refrigerator has been installed and commissioned to provide cooling for the new installation. The design incorporates several new features as improvements to the existing cryomodules. They include a four point support frame for the cavity strongback, a modified LN2 circuit internal to the cryomodule and a new design for the mechanical motion of the rf coupling loop. A summary of the design and the current status of the cryomodule production and supporting infrastructure will be presented.
TRIUMF, Vancouver
The ISAC superconducting linac is a fully operational machine that routinely provides beam to experiments. The linac consists of twenty superconducting independently phased cavities housed in five cryomodules. The initial tune is done manually aided by MATLAB routines to phase the linac and set the correct optics. From the initial tune we calculate the gradient at which each cavity operates based on the energy gain, the transit time factor and the geometry of the cavity itself. Then in the event of a gradient change of one or more cavities we can calculate the rf phase shift of each downstream cavity using the initial gradients, the known geometry of the entire linac and assuming linearity of the rf controls. This possibility has been investigated and we have demonstrated that the calculated phase shift can be implemented automatically thus avoiding a complete retune of the machine. In this paper we will present the calculations and the results of the online tests.
TRIUMF, Vancouver
Victoria University, Victoria, B.C.
TRIUMF, in collaboration with university partners, proposes to construct a megawatt-class electron linear accelerator (e-linac) as a driver for U(γ,f) of actinide targets for nuclear astrophysics studies, and 9Be(γ,p)8Li for beta-NMR materials science. The e-linac is part of a broader proposal for an expansion of the TRIUMF rare isotope beams capability through a new facility to be named ARIEL. The e-linac design and prospects for funding are elaborated.
TRIUMF, Vancouver
A personnel protection system is used to monitor the ion beam current into the experimental hall from the ISAC-II SC-linac. Two resonant capacitive pickups in the transfer line operate at the third harmonic of the bunch rate, 35.36 MHz, Ion charge, velocity and bunch width affect the sensitivity so calibration with dc Faraday cups is needed. Each monitor has a single conversion receiver with an active mixer. LO signals are provided by a frequency synthesizer locked to the accelerator synthesizer. The 1250 Hz IF signals are amplified, filtered with a 100 Hz bandwidth and amplitude detected. No image rejection is used as the background is due to on-frequency leakage from the RFQ and bunchers. An antenna in each monitor loosely couples a pulsed rf test signal to each pickup. These induced signals are mixed down to 11875 Hz, filtered, detected and used to provide watchdog signals. The measured currents are displayed through our EPICS control system which allows setting of the gain ranges, trip levels and conversion factors. The signals are also processed independently by dedicated ADC's and FPGA's to cause the Safety system to trip the beam if the current exceeds a nominal 10 nA.
TRIUMF, Vancouver
PAVAC, Richmond, B.C.
The medium beta section of the ISAC-II superconducting linac (β=5.7% and 7.1%) has been operational since April 2006 providing 20 MV of accelerating potential at 106 MHz. The ‘high beta' extension to the linac, in progress, will see the addition of twenty 141 MHz quarter wave cavities at β=11%. The design specification calls for cw operation at a voltage gain of at least 1.1 MV/cavity for no more than 7 W of power dissipated in the cavity. This operation point corresponds to challenging peak surface fields of 30 MV/m and 60 mT. The cavity design is similar in concept to the medium beta cavities except for the addition of a drift tube to render symmetric the accelerating fields. A prototyping and qualification program was initiated with PAVAC Industries Inc. of Richmond, B.C. Two full size models in copper and two in niobium have been completed. The niobium cavities have been warm and cold-tested and characterized for frequency, rf performance and mechanical stability. The cold performance of both cavities exceeds the specification and the final frequency is within tuning range. The design, fabrication details and test results will be presented.