Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session CD: Nuclear Instrumentation I |
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Chair: Corina Andreoiu, Simon Fraser University Room: Junior Ballroom C |
Friday, October 14, 2016 8:30AM - 8:42AM |
CD.00001: Progress towards the Advanced Cryogenic Gas Stopper at NSCL Kasey Lund, Georg Bollen, Antonio Villiari, Don Lawton, Dave Morrissey, Jack Otterson, Ryan Ringle, Stefan Schwarz, Chandana Sumithrarachchi, John Yurkon Beam stopping is the key to performing experiments with low-energy beams of rare isotopes produced by projectile fragmentation. Linear gas stoppers filled with helium have become reliable tools to accomplish this task. Further developments are underway to maximize efficiency and beam rate capability in order to increase scientific reach. Improvements include increasing extraction efficiency, lowering decay losses due to slow transport time, reducing molecular combination of the isotope of interest with background impurity gases, and minimizing space charge effects. The ACGS under construction at NSCL is designed to increase performance by overcoming some of the more common issues. The use of a 4-phase RF wire carpet to generate an electrical traveling wave speeds up the ion transport times. Cryogenic cooling of the helium gas chamber reduces molecular ion information. A geometry that puts the RF carpet in the mid-plane of the gas stopper alleviates space charge effects. Prototype testing of important ACGS components has been completed, specifically ion transport tests of the newly designed RF wire carpets. Transport efficiencies up to 95{\%} were demonstrated as well as transport speeds up to 100 m/s. [Preview Abstract] |
Friday, October 14, 2016 8:42AM - 8:54AM |
CD.00002: TITAN’s multiple-reflection time-of-flight isobar separator Moritz Pascal Reiter At the ISAC facility located at TRIUMF exotic nuclei are produced by the ISOL method. Exotic nuclei are separated by a magnetic separator and transported to TRIUMF’s Ion Trap for Atomic and Nuclear science (TITAN). TITAN is a system of multiple ion traps for high precision mass measurements and in-trap decay spectroscopy. Although ISAC can deliver some of the highest yields for even many of the most exotic species many measurements suffer from a strong isobaric background. This background often prevents the high precision measurement of the species of interest. To overcome this limitation an additional isobar separator based on the Multiple-Reflection Time-Of-Flight Mass Spectrometry (MR-TOF-MS) technique has been developed for TITAN. Mass selection is achieved using dynamic re-trapping of the species of interest after a time-of-flight analysis in an electrostatic isochronous reflector system. Additionally the MR-TOF-MS will, on its own, enable mass measurements of very short-lived nuclides that are weakly produced. Being able to measure all isobars of a given mass number at the same time the MR-TOF-MS can be used for beam diagnostics or determination of beam compositions. Results from the offline commissioning showing mass resolving power and separation power will be presented. [Preview Abstract] |
Friday, October 14, 2016 8:54AM - 9:06AM |
CD.00003: Construction of a multi-reflection time-of-flight spectrometer at the University of Notre Dame Brad Schultz The simultaneous production of rare isotopes and isobaric contaminants is a significant problem for precision measurements in nuclear and particle physics, which often require pure samples of a single species. Thus, a high-resolution, high efficiency beam purification method is required which is compatible with both low yields and the short half-life of the desired radionuclide. A multi-reflection time-of-flight mass spectrometer meets these criteria, while achieving resolving powers $>10^5$. Such a device has been constructed at the University of Notre Dame and will be installed in the ATLAS facility at Argonne National Lab for use as an isobaric purifier. The motivation and design will be presented. [Preview Abstract] |
Friday, October 14, 2016 9:06AM - 9:18AM |
CD.00004: Mass measurements of rare isotopes with the Single Ion Penning Trap Martin Eibach, Georg Bollen, Kerim Gulyuz, Christopher Izzo, Matthew Redshaw, Ryan Ringle, Rachel Sandler, Stefan Schwarz, Adrian Valverde High-precision mass data of atomic nuclei are integral for several different fields in fundamental research like investigations of fundamental interactions or nuclear structure studies. At the National Superconducting Cyclotron Laboratory rare isotope ions are produced by projectile fragmentation and subsequent in-flight separation. Using the Penning trap mass spectrometer LEBIT their mass can be measured with high precision using the time-of--flight ion cyclotron resonance (TOF-ICR) technique. However, it requires on the order of hundred detected ions for one mass measurement. As one moves further from the valley of stability, production rates of the exotic isotopes decline. In order to access rare isotopes being delivered at rates of about 1 ion/hour or less, a more sensitive technique is required. Therefore, the Single Ion Penning Trap (SIPT) is being developed, and will enable high-precision mass measurements with a single ion using the Fourier-Transform Ion Cyclotron Resonance (FT-ICR) technique. It aims for mass measurements around doubly magic rare isotopes far away from stability where the half-lives are usually sufficiently long for FT-ICR measurements. SIPT is currently being commissioned and ions have been sent through the beam line and detected in front of the magnet. [Preview Abstract] |
Friday, October 14, 2016 9:18AM - 9:30AM |
CD.00005: Simulations for a Multi-Reflection Time-of-Flight Mass Spectrometer at the University of Notre Dame James M Kelly, Catherine Nicoloff, Bradley E Schultz, Maxime Brodeur A multi-reflection time-of-flight mass spectrometer (MR-ToF) has been built at the University of Notre Dame. The MR-ToF will provide isobarically pure ion bunches to experiments at Argonne National Laboratory's (ANL) future ``N $=$ 126 Factory'', a unique facility capable of producing very neutron-rich nuclei around the N $=$ 126 shell closure. Prior to its installation at ANL, the MR-ToF is being evaluated in an off-line test setup consisting of a surface ion source, a Bradbury-Nielsen Gate (BNG) to chop the beam before injection into the MR-ToF, and a micro-channel plate detector to record the resulting bunches. The series of~simulations investigating the feasibility of this bunching method, as well as the injection of these bunches into the MR-ToF, will be presented. [Preview Abstract] |
Friday, October 14, 2016 9:30AM - 9:42AM |
CD.00006: Trapping in TITANs Cooler Penning Trap Brian Kootte, Daniel Lascar, Stefan Paul, Gerald Gwinner, Jens Dilling Penning trap mass spectrometry provides an excellent means of determining the masses of nuclei to high precision.Highly Charged Ions (HCIs) have been successfully used at TRIUMFs Ion Trap for Atomic and Nuclear science (TITAN) to enhance the precision of mass measurements for short-lived species. The gain in precision can theoretically scale with the charge state of the ion, but recent measurements of beam properties have shown that the process of charge breeding ions to higher charge states increases the energy spread of the ion bunch sent to the Penning trap. This reduces the gain from using HCIs. In order to maximize the precision of mass measurements, we are currently performing offline commissioning of a Cooler PEnning Trap (CPET) with the purpose of sympathetically cooling HCI bunches to an energy of \textasciitilde 1 eV/q using a plasma of electrons. This will require implementing a nested potential configuration to trap the ions and electrons in the same region so they can interact via coulomb scattering. Recent progress in testing the trapping of electrons and singly charged ions in CPET, leading towards the cooling of HCIs prior to mass measurements in TITANs will be discussed. [Preview Abstract] |
Friday, October 14, 2016 9:42AM - 9:54AM |
CD.00007: Instrumentation Upgrades to TITAN's Cooler Penning Trap Daniel Lascar The use of Highly Charged Ions (HCIs) is critical to improving the precision of Penning trap mass measurements of nuclides with half-lives substantially less than 100 ms, but the process of charge breeding imparts an unacceptably high energy spread to the ion bunch sent to TITAN's precision Penning trap for mass measurement. TITAN's Cooler PEnning Trap (CPET) at TRIUMF in Vancouver, Canada was designed to cool HCIs with a plasma of simultaneously trapped electrons. CPET is currently undergoing commissioning offline at TRIUMF. In order to prepare CPET for full operation, several technical challenges associated with the use of electrons in a strong magnetic field had to be overcome. First among these was the detection of electrons outside of CPET. A novel, thin charge-collecting detector was successfully developed. Known as the mesh detector, it is charge-agnostic and can be made effectively transparent to allow for the passage of any charged particle at the user's request. The second challenge, moving CPET's electron source off the central beam axis was overcome by the creation of an electron source which would allow for electron injection into CPET and the passage of cooled ions out of CPET. CPET's 7 T solenoid generates a stray field far outside of the magnet's central bore that forced the design of a set of electron injection optics that bend, steer and focus the beam in three dimensions. Results from the successful installation of these upgrades as well as a report on future work will be discussed. [Preview Abstract] |
Friday, October 14, 2016 9:54AM - 10:06AM |
CD.00008: CryoMPET: the Cryogenic Upgrade to TITAN`s Mass Measurement Penning Trap Erich Leistenschneider Atomic masses are key tools to understand the nature of nuclear forces. With the availability of beams of very exotic species, mass spectroscopy techniques have become more challenging. They need to be faster, more efficient, and still have to provide high enough precision to be of scientific value. The TITAN facility at TRIUMF has been performing precision mass measurements of radioactive nuclei for almost a decade. Its main equipment, the Measurement Penning Trap (MPET), employs the Time-of-Flight Ion Cyclotron Resonance technique to probe atomic masses of ions living as short as 10ms. A powerful way to increase the precision of such technique is to charge-breed the inspected ion, which, in order to prevent charge state decay through a typical measurement cycle, requires trap's vacuum level to be in the order of 1E-11 Torr. Otherwise, the ion's charge state will most likely decay via electron recapture from the trap's background gas. MPET is being redesigned to perform mass measurements of ions at charge states over +20. It will be integrated into a new cryogenic vacuum system and should be ready for commissioning in 2017. We will present the details of TITAN's new CryoMPET upgrade including its design concept and the status of its development. [Preview Abstract] |
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