Commissioning of the Cryogenic Current Comparator (CCC) at CRYRING
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D.M. Haider, A. Reiter, M. Schwickert, T. Sieber, T. Stöhlker, F. Ucar
GSI, Darmstadt, Germany
H. De Gersem, N. Marsic, W.F.O. Müller
TEMF, TU Darmstadt, Darmstadt, Germany
M. Schmelz, R. Stolz, V. Zakosarenko
IPHT, Jena, Germany
M. Stapelfeld
FSU Jena, Jena, Germany
T. Stöhlker
IOQ, Jena, Germany
T. Stöhlker, V. Tympel
HIJ, Jena, Germany
V. Zakosarenko
Supracon AG, Jena, Germany
Funding:Work supported by AVA - Accelerators Validating Antimatter the EU H2020 Marie-Curie Action No. 721559 and by the BMBF under contract No. 5P18SJRB1. Accurate non-destructive measurement of the absolute intensity of weak ion beams (< 1 uA) in storage rings is often restricted to special beam conditions and, even then, is associated with large uncertainties and tedious calibration procedures. However, experiments with rare ions in particular depend on excellent current resolution. In order to make these beams accessible, the Cryogenic Current Comparator (CCC) monitors deviations of the DC beam current on a scale of nA and compares the signal to a calibrated reference current. At the heavy-ion storage ring CRYRING at GSI a CCC prototype for FAIR was installed and first results of the commissioning are reported here. Preceding the operation with beam, a careful design of the beamline helium cryostat was required to provide the stable cryogenic environment needed for CCC operation. Mechanical and electro-magnetic perturbations that interfere with measurement of the beam’s faint magnetic field are suppressed by the internal structure of the system and a superconducting magnetic shield, while the remaining interference can be filtered with adequate signal processing. In this way, a current resolution in the nA range was demonstrated.
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Comparison of Feschenko BSM and Fast Faraday Cup with Low Energy Ion Beams
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R. Singh, W.A. Barth, P. Forck, S. Lauber, M. Miski-Oglu, T. Reichert, T. Sieber
GSI, Darmstadt, Germany
V.E. Scarpine, D. Sun
Fermilab, Batavia, Illinois, USA
A comparison between Fast Faraday Cup and Feschenko longitudinal bunch shape detectors was recently performed at HELIAC Advanced Demonstrator beamline at GSI. Feschenko bunch shape monitor (BSM) uses the time to space conversion by means of secondary electrons emitted from a wire correlated to a rf deflector, while the fast Faraday cup (FFC) measures the deposited charge in a cup geometry matched to 50 Ohm. The FFC design aims to minimize the bunch shape dilution due to field polarization and secondary electrons produced on irradiation. An He1+ with 100 µA average current and 1.4 MeV/u kinetic energy is utilized for this comparison. A buncher upstream of the detectors was operated to focus the beam longitudinally. The results are discussed in this contribution.
