First charge breeding of a rare-isotope beam with the electron-beam ion trap of the ReA post-accelerator at the National Superconducting Cyclotron Laboratory

Lapierre, A.; Schwarz, S.; Baumann, T.; Cooper, K.; Kittimanapun, Kritsada; Rodríguez, Ana Alonso; Sumithrarachchi, C.; Williams, S. J.; Wittmer, W.; Leitner, D.; Bollen, G.

doi:10.1063/1.4827308

Cited by 16 publications

(19 citation statements)

References 11 publications

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“…Experiments with stable 39 K ions result in a total charge breeding efficiency of up to 30% (calculated from the ion yield in all charge states compared to the incoming, singly charged ion current) and 6% for 39 K 15 + ions. 3 This efficiency can be predicted for a given current density by a simplified model of the ion capture in the EBIT. 7,18 For this purpose, the magnetic field configuration of 4 T in the Helmholtz region and 2 T in the solenoid has to be taken into account.…”

Section: Discussion Of the Resultsmentioning

confidence: 99%

“…7 The current density is also in satisfactory agreement with recent charge breeding efficiency measurements. 3 One of the goals for future developments of the ReA-EBIT is an increase of the electron beam current density. First steps currently taken are an increase of the magnetic field to a 4T-4T configuration and of the electron beam current to 1.4 A.…”

Section: Discussionmentioning

confidence: 99%

“…1 It accelerates low-energy beams obtained from gas stopping 2 of high-energy fragments to energies of up to several MeV/u. ReA employs a novel Electron Beam Ion Trap (EBIT) charge breeder 3 as an injector for a room-temperature radio-frequency quadrupole accelerator prior to further acceleration in a superconducting linear accelerator.…”

Section: Introductionmentioning

confidence: 99%

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Determination of the ReA Electron Beam Ion Trap electron beam radius and current density with an X-ray pinhole camera

Baumann

Lapierre

Kittimanapun

et al. 2014

Review of Scientific Instruments

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The Electron Beam Ion Trap (EBIT) of the National Superconducting Cyclotron Laboratory at Michigan State University is used as a charge booster and injector for the currently commissioned rare isotope re-accelerator facility ReA. This EBIT charge breeder is equipped with a unique superconducting magnet configuration, a combination of a solenoid and a pair of Helmholtz coils, allowing for a direct observation of the ion cloud while maintaining the advantages of a long ion trapping region. The current density of its electron beam is a key factor for efficient capture and fast charge breeding of continuously injected, short-lived isotope beams. It depends on the radius of the magnetically compressed electron beam. This radius is measured by imaging the highly charged ion cloud trapped within the electron beam with a pinhole camera, which is sensitive to X-rays emitted by the ions with photon energies between 2 keV and 10 keV. The 80%-radius of a cylindrical 800 mA electron beam with an energy of 15 keV is determined to be r 80% = (212 ± 19)μm in a 4 T magnetic field. From this, a current density of j = (454 ± 83)A/cm 2 is derived. These results are in good agreement with electron beam trajectory simulations performed with TriComp and serve as a test for future electron gun design developments.

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Section: Discussion Of the Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Determination of the ReA Electron Beam Ion Trap electron beam radius and current density with an X-ray pinhole camera

Baumann

Lapierre

Kittimanapun

et al. 2014

Review of Scientific Instruments

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“…Reacceleration of stable-isotope beams injected from the thermalized-beam area followed in early 2013 [3,16]. The ReA EBIT was brought on-line for the first time as part of commissioning in late 2013 [17]. It began on-line operation in September 2015 with the addition of an ion beam cooler and buncher (BCB) device for injection of pulsed beams.…”

Section: Introductionmentioning

confidence: 99%

First two operational years of the electron-beam ion trap charge breeder at the National Superconducting Cyclotron Laboratory

Lapierre

Bollen

Crisp

et al. 2018

Phys. Rev. Accel. Beams

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The electron-beam ion trap (EBIT) charge breeder of the ReA post-accelerator, located at the National Superconducting Cyclotron Laboratory (Michigan State University), started on-line operation in September 2015. Since then, the EBIT has delivered many pilot beams of stable isotopes and several rare-isotope beams. An operating aspect of the ReA EBIT is the breeding of high charge states to reach high reaccelerated beam energies. Efficiencies in single charge states of more than 20% were measured with 39 K 15þ , 85 Rb 27þ , 47 K 17þ , and 34 Ar 15þ. Producing high charge states demands long breeding times. This reduces the ejection frequency and, hence, increases the number of ions ejected per pulse. Another operating aspect is the ability to spread the distribution in time of the ejected ion pulses to lower the instantaneous rate delivered to experiments. Pulse widths were stretched from a natural 25 μs up to ∼70 ms. This publication reviews the progress of the ReA EBIT system over the years and presents the results of charge-breeding efficiency measurements and pulse-stretching tests obtained with stable-and rare-isotope beams. Studies performed with high sensitivity to identify and quantify stable-isotope contaminants from the EBIT are also presented, along with a novel method for purifying beams.

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“…The secondary beam of 72 Se was produced from the fragmentation of a 150 MeV/u 78 Kr primary beam and selected in the A1900 fragment separator [18]. The 72 Se ions were transported to the linear gas stopper, thermalized, and extracted before charge breeding to Q=17 + in NSCL's electron beam ion trap [19]. The charge-bred ions were then injected into the ReA3 accelerator chain and accelerated to an energy of 4.0 MeV/u.…”

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confidence: 99%

Localizing the Shape Transition in Neutron-Deficient Selenium

Henderson

Ash

et al. 2018

Phys. Rev. Lett.

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Neutron-deficient selenium isotopes are thought to undergo a rapid shape change from a prolate deformation near the line of beta stability towards oblate deformation around the line of N=Z. The point at which this shape change occurs is unknown, with inconsistent predictions from available theoretical models. A common feature in the models is the delicate nature of the point of transition, with the introduction of even a modest spin to the system sufficient to change the ordering of the prolate and oblate configurations. We present a measurement of the quadrupole moment of the first-excited state in radioactive ^{72}Se-a potential point of transition-by safe Coulomb excitation. This is the first low-energy Coulomb excitation to be performed with a rare-isotope beam at the reaccelerated beam facility at the National Superconducting Cyclotron Laboratory. By demonstrating a negative spectroscopic quadrupole moment for the first-excited 2^{+} state, it is found that any low-spin shape change in neutron-deficient selenium does not occur until ^{70}Se.

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First charge breeding of a rare-isotope beam with the electron-beam ion trap of the ReA post-accelerator at the National Superconducting Cyclotron Laboratory

Cited by 16 publications

References 11 publications

Determination of the ReA Electron Beam Ion Trap electron beam radius and current density with an X-ray pinhole camera

Determination of the ReA Electron Beam Ion Trap electron beam radius and current density with an X-ray pinhole camera

First two operational years of the electron-beam ion trap charge breeder at the National Superconducting Cyclotron Laboratory

Localizing the Shape Transition in Neutron-Deficient Selenium

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