The results of comfort test indicated that subjects preferred type A shoes which has low cut and thinner outsole. Overall comfort rate of type A shoes showed 84.7 9.1% compared to B (78 14.7%), C (63.2 16.9%) and D (64 15.8%). Subjects tended to have smaller peak ankle angle (ankle eversion, abduction and plantar flexion angle) when wearing type A shoes during walking compared to type B and C shoes (Figure 2, P5 0.05). Also, subjects tended to have lower peak ankle inversion and abduction moment when wearing type A shoes compared to type B, C, and D shoes (Figure 2, P5 0.05).

The TRIUMF cyclotron was originally conceived for several proton beams extracted simultaneously at different energies. Recent operation includes a 500 MeV beam up to 150 μA for meson users, a 500 MeV beam up to 80 μA for rare isotope production, and a 100 MeV beam up to 70 μA for medical isotopes. Extraction of a second primary beam for ISAC has now been given priority. A necessary characteristic for the primary beams for ISAC is intensity stability better than 1% to allow the highest target temperature (and therefore the most efficient yield of rare ions) to be maintained. An operational solution for stabilization of the existing beam has been shown to be applicable to both beams because of the particular angular separation between the two stripping foils in the cyclotron. Stability dependence from the angular foil separation in the cyclotron is illustrated.

A new series of experiments (mainly astrophysics) began at TRIUMF in July 2001 when the ISAC-I linear accelerator began delivering up to 1.5 MeV/u radioactive ion beams (RIB) to users. A superconducting linear accelerator extending the RIB energy to 6.5 MeV/u has recently been approved and is now being constructed (ISAC-II). Record RIB intensities are being achieved from different target ion sources with a primary incident proton beam of 500 MeV, up to 50 /spl mu/A intensity. This will later be increased to 100 /spl mu/A, compatibly with target acceptance. Furthermore, an additional 100 /spl mu/A extracted proton beam is being considered for simultaneous (RIB) production from a second target-ion source system. This would significantly enhance the research potential of the laboratory. Four simultaneous high-intensity extracted beams would therefore be required for a total maximum cyclotron accelerated current of about 400 /spl mu/A. Recently we have been able to deliver 300 /spl mu/A to the existing three high intensity beam lines at 90% duty cycle. The cw delivery of beam was limited only by the presently available external beam dump capacity. In this paper we will review the present operational experience at 200/250 /spl mu/A, the future plans for intensity upgrade to 350/400 /spl mu/A, and the intrinsic factors limiting the total accelerated intensity beyond 400 /spl mu/A.

The TRIUMF cyclotron routinely accelerates ∼220 μA of H− ions, extracting protons simultaneously to four external beam lines. The radioactive beam facility ISAC, now operating at 10–20 μA ∼500 MeV protons, will soon require up to 100 μA at 500 MeV. The CHAOS experiment on the π+, π− secondary beam line also requires a high intensity beam (∼140 μA, 500 MeV) but with a short (2 ns) bunch length. High current operation with 2 ns beam has been facilitated by the 4th harmonic auxiliary acceleration cavity [4]. The 2 ns beam structure is now achieved by phase compression as the energy gain per turn increases near extraction. The paper focuses on improvements in the reliability of this cavity and its rf coupler. The higher energy gain per turn also reduces H− stripping losses (by about 33%) in the high energy region, hence increases the allowed beam intensity for a given beam activation. The total current will soon be increased to about 300 μA to allow for ISAC requirements.

A LabVIEW program running on a Sun SPARCstation 5 controls a Tektronix TDS820 6 GHz sampling oscilloscope via an Ethernet to GPIB adapter. A PC based X Window terminal continuously displays the trace, refreshed at 7 Hz. Functions such as gain, time base and application specific controls are selected by menus, buttons and dialog boxes. We have used the system to observe signals from fast (>1 GHz) Faraday cups (FFC) in the radio frequency quadrupole (RFQ) section of our Radioactive Beam Facility (ISAC). The setup utilizes the accelerator control display terminals while allowing the oscilloscope to be closer to the FFCs. ISAC uses the RFQ to accelerate singly charged ions to 0.15 MeV/u where they are stripped prior to acceleration in a drift tube linac (DTL). The time structure of the beam at the RFQ entrance was measured on a FFC placed 4 m downstream of the RFQ pre-buncher. Additional 50 Omega coaxial cone FFCs were installed downstream of the RFQ near the RFQ exit, just ahead of the stripping foil and at a double focus following the charge selection slit. The last FFC shows the increase in the mean drift time and broadening associated with the increase in energy loss and straggling caused by foil thickening under ion bombardment. Although the phase broadening cannot be corrected, the increase in the mean drift time can be corrected by changing the bias voltage on the stripper foil and thus keeping the ions in phase with the rebuncher rf.

The ISAC 35 MHz RFQ is designed to accelerate ions of A/q up to 30 from 2keV/u to 150keV/u in cw mode. The RFQ structure is 8 meters long and the vane-shaped rods are supported by 19 rings spaced 40 cm apart. An unusual feature of the design is the constant synchronous phase of -25; the buncher and shaper sections are eliminated in favor of an external multi-harmonic buncher. All 19 rings are installed with quadrature positioning of the four rod electrodes aligned to +/- 0.08 mm. Relative field variation and quadruple asymmetry along the 8 meters of the RFQ was measured to be within +/- 1%. Early operation at peak inter-electrode voltage (75kV) was restricted by the rapid growth of dark currents due to field emission; the nominal operating power of 75 kW increased to 100 kW in a few hours. A program of high power pulsing, followed by cw operation have all but eliminated the problem leading to a successful 150 hour test at full power. Successful beam test results confirm beam dynamics and rf designs.

The ISAC 35 MHz split-ring RFQ is designed to accelerate ions of A/q/spl les/30 from 2 keV/u to 150 keV/u in cw mode at a constant synchronous phase of -25/spl deg/. Beam tests with 7 of the 19 split rings installed (E/sub fin/=0.55 keV/u) have recently been completed. The tests demonstrated that a constant synchronous phase RFQ with external buncher works splendidly for low beta, low intensity applications. One peculiar aspect of the RFQ is that the longitudinal acceptance is larger for beams injected off-center. The test set-up and results of both the measurements and the simulations are presented and discussed.

ISAC, a new facility for exotic nuclei is under construction at TRIUMF. The radioactive ions will be produced by the ISOL technique with currents up to 100 mu A of 500 MeV protons impinging on target/ion source stations located in an underground vault. Following mass selection the beam is further transported with up to 60 keV energy to either a low energy area or to an RFQ followed by a DTL. The beam from the DTL will. have energy continuously variable from 0.15 to 1.5 MeV/u. A new 480-500 MeV proton beam has already been extracted from the TRIUMF cyclotron simultaneously with three existing variable energy beams. A 5000 m(2) building has now been completed. A 60 keV off-line source, part of the LEBT, a 11.67 MHz prebuncher, an 8 m long RFQ tank, and seven front-end modules of the split ring 4-rod RFQ system have been installed, aligned and are being commissioned. Beam tests through the RFQ front end will be under way at full cw power during summer 1998. Low energy (60 KeV) experiments using exotic ions are planned for year end. Other recent TRIUMF progress, including new records for the OPPIS high intensity polarized beams and highlights of cyclotron applications will also be summarized.

In the 14(th) Int. Conf. On Cyc. held at Cape Town, 1995, we reported a 2.5 mA H- cyclotron beam capability using a 28 keV, 15 mA do injection. Baartman pointed out that the upper limit should be about 3.3 mA for our model cyclotron. In order to test whether we can reach such a limit, a cesiated H- source and a 5-electrode extraction system have been developed. More than 20 mA dc beam with a normalized 4 rms emittance of 0.5 pi-mm-mrad has been obtained. As a result, 1.8 mA accelerated rf beam at 0.9 MeV is achieved using 50% duty factor but without injection bunching, equivalent to a 3.6 mA far the full power. The magnet profile of the model cyclotron and its effect on the bunching gain factor at energies 0.3, 0.5 and 0.9 MeV (resp. 1.5, 2.5 and 4.5 turns) were studied.

An 8 m long split-ring RFQ linac is being constructed at TRIUMF as part of the ISAC radioactive beam project. The RFQ is designed to accelerate unstable nuclei with q/A greater than or equal to 1/30 from 2 keV/u to 150 keV/u. Several unusual beam dynamics studies have been pursued during the latter stages of the design. To furnish engineering alignment tolerances, particle tracking in the 10-term potential was performed to estimate the RFQ performance with respect to vane displacement errors; the results are compared with a simple analytical model. In order to explore fringe held effects, particle tracking studies through computed three-dimensional fields at the RFQ entrance and exit were made to optimize the radial matching section (RMS) to the LEBT optics, and to appraise the value of a transition cell[9]. In this paper we describe the methods and results of the beam dynamics simulations and summarize final specifications for the RFQ.

ISAC, a new facility for accelerating intense beams of unstable ions, is under construction at TRIUMF. The radioactive nuclei will be produced by up to 100 A of 500 MeV protons impinging on one of two target/ion source stations located in an underground vault. The ionized beam will be transported by electrostatic ion optics to a high acceptance, high resolution mass analyser. Following mass selection the beam is transported vertically to grade level and then horizontally to either a low energy experimental area or to a system of accelerators. First, a 35 MHz cw RFQ accelerates isotopes with q/A >1/30 from 2 keV/u to 150 keV/u. Following the RFQ the beam is passed through a stripper and magnetic bend to select a charge state with q/A 1/6 prior to rebunching and injection into a cw drift tube linac (DTL) operating at 105 MHz. The output beam, with energy continuously variable from 0.15 to 1.5 MeV/u, is transported to one of a number of experimental stations. This paper briefly outlines the plans, schedule and status of the project.

A radioactive ion beam (RIB) facility is being built at TRIUMF. A novel design for the target/ion source station will allow us to bombard a thick target with TRIUMF's 100 μA, 500 MeV proton bam, producing a variety of very intense beams of nuclei far from stability. After mass separation the beams can be sent to two different experimental areas. One uses the 60 keV energy beam and the second one will use the 0.15 to 1.50 MeV/u post-accelerated beam. Singly charged ion beams, with A ≤ 30 delivered from the on line mass separator, with an energy of 2 keV/u, will be accelerated in a two stage linac consisting of an RFQ and a post-stripper drift-tube linac up to 1.5 MeV/u. CW operation mode is required to preserve beam intensity. As a consequence of the low q/A ions a low operating frequency for the RFQ is required to achieve adequate transverse focusing. The main features of this accelerator are: 35 MHz RFQ, stripping at 150 keV/u, beam energy continuously variable from 0.15 to 1.50 MeV/u and CW operation.

Two versions of injection line matching sections between the external ion source and the spiral inflector are used for the compact cyclotrons developed at TRIUMF in cooperation with Ebco Technologies. The 30 MeV model adopts a solenoid-doublet (SQQ) version while the 19 MeV unit takes a four quadrupole/two quadrupole (4Q/2Q) option. Both cyclotrons use a same type of H cusp source and an identical inflector-central region combination. A comparison has been made between these two systems, in terms of DC transmission and RF acceptance as a function of source's H current intensity and emittance. The design and optics characteristics for both systems are described and the results obtained are reported

This paper describes the ISAC-1 radioactive ion beam facility proposed at TRIUMF. A novel approach for the target/ion source station will allow an incident proton beam intensity of at least 10 /spl mu/A at 500 MeV. This should give high luminosity for the production of nuclei far from stability with a very large isotopic range. After mass separation the beams can be sent to two different experimental areas. One uses the 60 keV energy beam for experiments such as the neutral atoms trap, parity violation, etc. The second one, mainly dedicated to nuclear astrophysics, will use the 0.2 to 1.5 MeV/u post-accelerated beam. Singly charged ion beams, with A/spl les/30 delivered from the on line mass separator, with an energy of 2 keV/u, will be accelerated in a two stage linac consisting of an RFQ and a post-stripper drift-tube linac up to 1.5 MeV/u. CW operation mode is required to preserve beam intensity. As a consequence of the low charge to mass ratio of the ions a low operating frequency for the RFQ is required to achieve adequate transverse focusing. The main features of this accelerator are: 35 MHz RFQ, stripping at 150 keV/u, and beam energy continuously variable from 0.2 keV/u to 1.5 MeV/u.

A short axial injection line using either four or two identical quadrupoles for phase space matching between an external H cusp source and the central region of a compact cyclotron has been tested, optimized and commissioned The facility used for the tests consists of a H -source and extraction system. a changeable axial injection column and an I MeV central region model cyclotron 270 PA ofH at I MeV was obtained without bunching, for a 2 mA DC source output The system is adopted for the injection into a 19 MeV cyclotron ( TR13 ).

An iron-core current compensated magnetic channel has been built as part of the TRIUMF 450 MeV Hextraction feasibility project. The channel would operate in the 0.5 T cyclotron field and was designed using the two-dimensional code POISSON. Recent heam tests with the channel installed in the TRIIJMF cyclotron confirmed that the electro-mechanical design is reliable and that the effect on the circulating beam is in agreement with calculation. The design and hardware details will be described and the beam test results reported.

The design, testing and selection of a compact modular injection system for the TR13 cyclotron's externally injected 2 mA H- ion beam is presented in this paper. Concurrent design techniques, and proto-type evaluation on a 1 MeV test cyclotron are discussed. Key results include comparisons of simulated and measured parameters, beam transmission as a function of injection system rotation angle, and full beam scintillator images in the vicinity of the inflector exit.

The efficiency of the proposed H/sup -/ extraction in the TRIUMF cyclotron is improved by inducing a precessional component to the radius gain per turn by exciting a coherent radial betatron oscillation at /spl nusub r/=3/2. Beam test and computer simulation results show that accompanying this improvement is a growth in the transverse emittance of the extracted beam. The growth is, in part, due to phase-dependent mixing of the perturbed beam. This phase-dependence can be greatly reduced by flattopping the local energy gain per turn with the addition of a higher harmonic accelerating field in phase opposition to the fundamental. A 92 MHz, 4/sup th/ harmonic, /spl lambda4 cavity installed in the TRIUMF cyclotron has been used for such a purpose. Results of both computer simulations and beam tests will be presented.< >

The concepts of percolation theory have been useful in describing the transport of matter or energy in condensed matter.1 Both lattice and continuum models have received considerable attention. For lattice problems, Monte Carlo simulation has been quite effective in determining critical thresholds and exponents. Alternatively, real-space renormalization group methods have also been successful.2 We have devised a renormalization group method, which is based on the finite-size scaling hypothesis,3 and which can be generalized easily to study quantum percolation (to be described below).