Ayet, S.

Bergmann, J.

Dickel, T.

Ebert, J.

Geissel, H.

Haettner, E.

Hornung, C.

Jesch, C.

Lang, J.

Lippert, W.

Pikhtelev, A. R.

Plaß, Wolfgang

Purushothaman, S.

Reiter, M. P.

Rink, A.-K.

Scheidenberger, C.

Yavor, M. I.

GSI Repository

Recent Technical Improvements for the Multiple-Reflection Time-of-FlightMass Spectrometer at the FRS Ion Catcher∗S. Ayet1,2, J. Ebert1, T. Dickel1,2, W. R. Plaß1,2, J. Bergmann1, H. Geissel1,2, E. Haettner2,C. Hornung1, C. Jesch1, J. Lang1, W. Lippert1, A. R. Pikhtelev3, S. Purushothaman2, M. P. Reiter1,A.-K. Rink1, C. Scheidenberger1,2, and M. I. Yavor41Justus-Liebig-Universita¨t, Gießen, Germany; 2GSI, Darmstadt, Germany; 3Institute of Energy Problems of ChemicalPhysics of the Russian Academy of Science, Chernogolovka, Russia; 4Institute for Analytical Instrumentation of theRussian Academy of Sciences, St. Petersburg, RussiaThe multiple-reflection time-of-flight mass spectrometer(MR-TOF-MS) [1, 2] is part of the FRS Ion Catcher exper-iment [3], which serves as a test facility for the Low EnergyBranch (LEB) of the Super-FRS at FAIR. At the FRS IonCatcher, range-bunched nuclides from the FRS are stoppedin a novel cryogenic stopping cell (CSC)[4], extracted andtransported via an RFQ system to the MR-TOF-MS. At theLEB, the MR-TOF-MS will perform mass measurements,isobar separation and broadband mass spectrometry for ionidentification and diagnostics purposes.A unique feature of the MR-TOF-MS is its capability ofshifting the potential of the incoming ions [5]. The poten-tial shift is effected by pulsing the storage potential in theinjection trap in front of the time-of-flight analyzer withina few tens of nanoseconds by a high voltage (HV) pulser.Thus the MR-TOF-MS can accept ions at different entrancepotetials, which may be required e.g. if the MR-TOF-MS isused at different RIB facilities, without the need of placingthe MR-TOF-MS on a high-voltage platform. The ampli-tude of this potential shift has been increased from 750 Vto 1300 V. For an ion entrance potential close to ground,the kinetic energy of the ions in the time-of-flight analyzertherefore also was increased increased to 1.3 keV. This in-crease in kinetic energy will reduce the turn-around timeand the emittance of the ions in the analyzer. Hence themass resolving power and mass accuracy will be increased,while decreasing the time-of-flight required to achieve agiven mass-resolving power [5].The stability of the voltages of the analyzer electrodesare of primary importance for long-term high-accuracymass measurements. A new voltage stabalization was de-veloped and commissioned together with new high volt-age power supplies for the MR-TOF-MS. Fig. 1 shows thevoltage stability achieved with the new electronics. Overa measurement period of 330 minutes, the rms deviationof the time-of-flight now amounts to 0.5 ppm only. Thisexceptional performance will enable direct mass measure-ment of rare exotic nuclei at very high mass measurementaccuracy.A new data acquisition software has been developed forthe MR-TOF-MS. It supports a variety of data acquisi-∗This work was supported by the BMBF under contracts no.06GI9114I and 05P12RGFN8, by the state of Hesse (LOEWE CenterHICforFAIR) and by JLU Gießen and GSI under the JLU-GSI strategicHelmholtz partnership agreementFigure 1: Stability of the mass measurement[6] of 133Csions over a time period of 330 minutes. The time-of-flightamounts to 5.843 ms, and a mass resolving power (FWHM)of more than 150,000 is achieved. The rms value of thetime-of-flight is about 0.5 ppm.tion hardware, including different TDCs and ADCs. Thesoftware also allows real-time data processing during themeasurement such as mass calibration of the time-of-flightspectra, peak detection, and the online identification ofmasses.In an upcoming beam time with the CSC at the FRS IonCatcher, the MR-TOF-MS will be the key device for theperformance characterization of the CSC. In particular, itwill be used to identify β-decaying 238U fission fragmentsextracted from the CSC by their mass values and to performisobar separation with short-lived nuclei.References[1] W. R. Plaß et al., Nucl. Instrum. Methods B 266 (2008) 4560.[2] T. Dickel, PhD Thesis, 2010, JLU Gießen.[3] W. R. Plaß et al., Nucl. Instrum. Methods B 317 (2013) 457.[4] S. Purushothaman et al., Eur. Phys. Lett. 104 (2013) 42001.[5] W. R. Plaß et al., Int. J. Mass Spectrom. 394 (2013) 134 .[6] J. Lang, PhD thesis in preparation.GSI SCIENTIFIC REPORT 2013 NUSTAR-FRS-10doi:10.15120/GR-2014-1-NUSTAR-FRS-10 107

Recent Technical Improvements for the Multiple-Reflection Time-of-Flight Mass Spectrometer at the FRS Ion Catcher

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Recent Technical Improvements for the Multiple-Reflection Time-of-Flight Mass Spectrometer at the FRS Ion Catcher

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