Beam commissioning and first operation of the ISAC DTL at TRIUMF

Abstract

The post-accelerator for the ISAC radioactive beam facility combines a 35.4 MHz RFQ and a variable energy 106 MHz DTL. The ISAC DTL is designed to accelerate ions with 3 ≤ A/q ≤ 6 to energies fully variable from 0.153 to 1.53 MeV/u. The unique separated function design allows efficient room-temperature acceleration and full energy variability with no degradation in beam quality. The first stable beams were accelerated in the DTL in Dec. 2000 with full commissioning in the first months of 2001. Test results with stable beam will be reported and compared to beam simulation results. In addition the initial operating experience with stable beam delivery is reported.

Physics with reaccelerated radioactive beams at TRIUMF-ISAC

“…Such particle energy spectra provided an accurate measure of the A = 29 beam composition as 72.0(8)% 29 Na and 28.0(8)% 29 Al, and hence a determination of the fraction of the 110 Pd Coulomb excitation peak in figure 23(a) resulting from each of 29 Na and 29 Al beam particles. Taking this beam composition into consideration, the γ -ray yields were fit with the multi-step GOSIA [128] Coulomb excitation code and combined with the well-known B E2; 0 + gs → 2 + 1 = 8446(441)e 2 fm 4 in 110 Pd [153] to yield the unknown 29 Na reduced transition matrix element 5 2 + 1 E2 3 2 + gs = 0.237 (21)eb [154]. This first transition matrix element measurement for neutron-rich 29 Na is in good agreement with the aforementioned SDPF-M prediction of 0.232 eb and, together with the ordering of the lowlying 3 2 + gs and 5 2 + 1 levels (which is correctly predicted by the SDPF-M calculations, but inverted in the pure sd-shell USD calculations), the previous ground-state static quadrupole moment measurement for 29 Na [155], and recent studies of 29 Na via β-decay [156], provides strong evidence in support of the interpretation of the low-lying states in 29 Na as admixtures of 0p-0h and 2p-2h configurations that represent the transition from traditional sd-shell model configurations to the 'island of inversion'.…”

“…Low-energy (<60 keV) RIBs have been available at ISAC since spring 1999. Approximately 2 years later an RFQ [4] and variable energy DTL [5] became operational to provide reaccelerated radioactive beams in the energy range from 0.15 to 1.8 A MeV for nuclear reaction studies of importance in explosive nucleosynthesis environments such as novae and x-ray bursts. The instruments developed for these challenging experiments include (1) the DRAGON (Detector of Recoils And Gamma rays Of Nuclear reactions) recoil separator designed to measure radiative capture of RIBs on hydrogen and helium target nuclei, (2) the TUDA (TRIUMF UK Detector Array) charged particle detector array and (3) TACTIC, an active target time projection chamber.…”

Efficient continuous wave accelerating structure for ion beams

“…The best candidate for the cw RT structure is an H-type drift-tube resonator [3,4]. Interdigital H-type (IH) structures are known for high shunt impedance, see, e.g., [5,6] and have been used in cw heavy ion linacs at low energies, typically below 1.5 MeV=u [7]. There are several operational pulsed linacs based on IH structures up to energies of 6 MeV=u.…”

Dual Frequency Enhancement of the Supernanogan Multi-Charged Ion Source at TRIUMF ISAC Facility

“…The primary accelerator Radio Frequency Quadrupole (RFQ) [5] is designed to accept beams at a fixed injection velocity of 2.04 keV/u. Moreover, the secondary accelerator Drift Tube Linac (DTL) [6] requires a mass-over-charge ratio between 3.0 and 6.0. Since the source extraction voltage is limited to 65 kV, a multi-charge ion source MCIS was needed to deliver beams above mass 32.…”