Off-line ion source terminal for ISAC at TRIUMF

Abstract

The off-line ion source (OLIS) terminal consists of a microwave cusp ion source, either a surface ion source or a hybrid surface-arc discharge ion source and an electrostatic switch that allows selecting any one of the sources without mechanical intervention. These sources provide variety of beams to ISAC experiments, for commissioning the accelerators, for setting up the radioactive experiments, and for tuning the beam lines. The microwave ion source has been operational since 1995 and provides singly and doubly charged beams from various stable isotopes for many ISAC experiments at high and low energy areas. Originally its prime goal was to provide beams from gaseous elements, but later two ovens and a sputtering system were added in order to provide beams from liquids and from solids. The surface ion source installed in 2002 can provide low energy spread beams from alkali and semialkali elements. It also has three separate ovens and an ionizer. Therefore, it can provide three different temperature regions simultaneously to provide different beams to ISAC. It is mainly used for laser spectroscopy experiments and other experiments, which require a finite beam quality. A hybrid surface-arc discharge ion source was also developed and installed in order to meet specific demands from experiments. This source terminal is now automated for start up and for mass selection. It is capable of providing stable beams for months without maintenance and it is also capable of providing negative ion beams if required. To date, over 40 different isotopes including many rear isotopes were delivered to various experiments from the OLIS source terminal. Performances of the ion sources and some of the results are discussed.

Strength of theEc.m.=1113keV resonance in20NeChristian1, Hutcheon2, Akers3 et al. 2013Phys. Rev. C

“…2. The result is σ DC = 0.52 ± 0.06 µb, which implies a 17% decrease in the S-factor of Rolfs et al This represents the maximum potential change since inclusion of the 16 O (p, γ) 17 F normalization would tend to increase the the DC → 2425 keV cross section.…”

“…They also perform a separate normalization to 16 To examine the effect of a change in ωγ 1113 on the astrophysical S-factor, we renormalize the DC → 2425 keV cross section using Eq. (4), taking ωγ 1113 as 0.931 ± 0.045 eV, the weighted average of the strengths shown in Fig.…”

“…This experiment also served as commissioning of a new timestamp-based data acquisition system that will be detailed in an upcoming technical paper. An isotopically pure beam of 20 Ne (5+) was extracted from the ISAC offline microwave ion source [16] and accelerated to an energy of 1163 keV/u before being delivered to the DRAGON experimental station with an average intensity of (9.3 ± 0.1) × 10 10 s −1 . The 20 Ne beam impinged on the DRAGON windowless gas target, which was filled with H 2 gas at an average pressure of 4.81 ± 0.01 Torr.…”

“…The cross section of 20 Ne (p, γ) 21 Na has been measured in the range of E cm = 0.35-2.0 MeV (E lab = 0.37-2.1 MeV) by Rolfs et al [1] and extrapolated to stellar energies. This experiment did not measure absolute yields and instead relied on normalization to the previously measured E cm = 1113 keV (E lab = 1169 keV) resonance as well as 16 O (p, γ) 17 F direct capture. The "known" value of the E cm = 1113 keV resonance was taken from Ref.…”

First Use of High Charge States for Mass Measurements of Short-Lived Nuclides in a Penning Trap

“…A summary of the trapping and rf-schemes are listed in Tab.I together with the measured frequency ratio R = ν ref c /ν meas c to the reference ion, 85 Rb 9+ . 85 Rb + was delivered at the same beam energy from TRIUMF's off-line ion source (OLIS) [28]. A fraction of the mass A = 74 beam from ISAC was 74 Ga, and we have determined its mass as well.…”