2. Beam charge and current monitors
Paper Title Page
MOOC03 The Removal of Interference Noise of ICT using the PCA Method 22
 
  • J. Chen, Y.B. Leng, L.Y. Yu
    SINAP, Shanghai, People's Republic of China
  • N. Zhang
    SSRF, Shanghai, People's Republic of China
 
  The measurement of beam charge is a fundamental re-quirement to all particle accelerators facility. Shanghai soft X-ray free-electron laser (SXFEL) started construc-tion in 2015 and is now in the commission phase. Al-though integrated current transformer (ICT) were installed in the entire FEL for the measurement of the absolute beam charge, the accurate measurement becomes difficult in the injector and the main accelerator section due to the noise interference from external factors such as klystron modulator. The evaluation of the source of noise signals and the procession of noise reduction using the principal component analysis (PCA) are proposed in this paper. Experiment results show that PCA method can effectively remove the interference of lower frequency noise from the klystron modulator and it can also improve the resolution of the ICT system. Detailed experiment results and data analysis will be mentioned as well.  
slides icon Slides MOOC03 [2.520 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOOC03  
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MOOC04
Bunch Charge Monitor for the ALS Upgrade  
 
  • S. De Santis, D. Li, W.E. Norum, G.J. Portmann
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The ALS upgrade project (ALS-U) consists in the replacement of the existing ALS storage ring with a new storage and accumulator rings. Due to the reduced lifetime of the ultra-low emittance beam circulating in the new storage ring, trains of 25/26 bunches have to be swapped between storage and accumulator every 30-60 seconds. The depleted train swapped out to the accumulator is topped back to its nominal charge from the injector and swapped back into the storage ring at the next injection cycle. Monitoring the bunch charge and parasitic bunches is necessary to minimize stored current variations in the storage ring and beam losses during the injection/extraction process. We present a bunch charge monitor based on a broadband analog-to-digital converter that allows to sample the signal obtained from a beam pickup at a frequency resulting in a scan of the entire ring with a ~60 ps resolution every 60 microseconds. Hundreds of scans are accumulated to obtain the necessary charge resolution. The beam pickup has been designed to be insensitive to the beam transverse position and its response to a bunch passage decays so rapidly that the readout is not affected by adjacent bunches.
 
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MOPC03 Precise Measurement of Small Currents at the MLS 118
 
  • Y. Petenev, J. Feikes, J. Li, A.N. Matveenko, Y. Tamashevich
    HZB, Berlin, Germany
  • R. Klein, J. Lubeck, R. Thornagel
    PTB, Berlin, Germany
 
  The Physikalisch-Technische Bundesanstalt (PTB), the National Metrology Institute of Germany, utilizes an electron storage ring - the Metrology Light Source (MLS), located in Berlin, as a radiation source standard in the VIS, UV and VUV spectral range. In order to be able to calculate the absolute intensity of the radiation, the electron beam current has to be measured with low uncertainty. In this paper we focus on the measurement of the beam current in a range of several nA to 1 pA (one electron) by means of Si photodiodes, detecting synchrotron radiation from the beam. Electrons are gradually scraped out of the ring and the diode signal is analyzed afterwards. The exact number of stored electrons then can be derived from the signal. The measurement is carried out automatically with an in-house developed software.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC03  
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MOPC04 Beam Charge Measurement and System Calibration in CSNS 122
 
  • W.L. Huang, F. Li
    CSNS, Guangdong Province, People's Republic of China
  • L. Ma, S. Wang, T.G. Xu
    IHEP, Beijing, People's Republic of China
 
  In China Spallation Neutron Source(CSNS), the beam charge monitors along the ring to the target beam transport line(RTBT) and the ring to the dump beam transport line(RDBT), are consisted of an ICT and three FCTs manufactured by Bergoz. The electronics includes a set of NI PXIe-5160 oscilloscope digitizer, and a Beam Charge Monitor(BCM) from Bergoz as supplementary. The beam charge monitors provide the following information: a) the quantity of protons bombarded the tungsten target; b) the efficiency of particle transportation; c) a T0 signal to the detectors and spectrometers of the white neutron source. With the calibration with an octopus 50Ω terminator in lab and an onboard 16-turn calibrating coils at the local control room, corrections for the introducing the 16-turn calibrating coils and the long cable were made. An accuracy of ±2% for the beam charge measurement during the machine operation has been achieved with the ICT/FCTs and a PXIe-5160 oscilloscope digitizer.  
poster icon Poster MOPC04 [3.082 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC04  
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MOPC06 Comparative Measurement and Characterisation of Three Cryogenic Current Comparators Based on Low-Temperature Superconductors 126
 
  • V. Tympel, T. Stöhlker
    HIJ, Jena, Germany
  • H. De Gersem, N. Marsic, W.F.O. Müller
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M.F. Fernandes, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • M.F. Fernandes, J. Tan
    CERN, Geneva, Switzerland
  • M.F. Fernandes, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • J. Golm, R. Neubert, F. Schmidl, P. Seidel
    FSU Jena, Jena, Germany
  • D.M. Haider, F. Kurian, M. Schwickert, T. Sieber, T. Stöhlker
    GSI, Darmstadt, Germany
  • R. Neubert
    Thuringia Observatory Tautenburg, Tautenburg, Germany
  • M. Schmelz, R. Stolz
    IPHT, Jena, Germany
  • T. Stöhlker
    IOQ, Jena, Germany
  • V. Zakosarenko
    Supracon AG, Jena, Germany
 
  Funding: Supported by the BMBF, project numbers 05P15SJRBA and 05P18SJRB1.
A Cryogenic Current Comparator (CCC) is a non-destructive, metrological-traceable charged particle beam intensity measurement system for the nano-ampere range. Using superconducting shielding and coils, low temperature Superconducting Quantum Interference Devices (SQUIDs) and highly permeable flux-concentrators, the CCC can operate in the frequency range from DC to several kHz or hundreds of kHz depending on the requirement of the application. Also, the white noise level can be optimized down to 2 pA/sqrt(Hz) at 2.16 K. This work compares three different Pb- and Nb-based CCC-sensors developed at the Institute of Solid State Physics and Leibniz Institute of Photonic Technology at Jena, Germany: CERN-Nb-CCC, optimized for applica-tion at CERN Antiproton Decelerator (AD) in 2015 with a free inner diameter of 185 mm; GSI-Pb-CCC, designed for GSI-Darmstadt with a free inner diameter of 145 mm, 1996 completed, 2014 upgraded; GSI-Nb-CCC-XD, de-signed for the GSI/FAIR-project with a free inner diame-ter of 250 mm, 2017 completed. The results of noise, small-signal, slew-rate, and drift measurements done 2015 and 2018 in the Cryo-Detector Lab at the University of Jena are presented here.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC06  
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MOPC08 Beam Intensity Monitoring with nA Resolution - the Cryogenic Current Comparator (CCC)* 130
 
  • D.M. Haider, P. Forck, F. Kurian, M. Schwickert, T. Sieber, T. Stöhlker
    GSI, Darmstadt, Germany
  • H. De Gersem, N. Marsic
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M.F. Fernandes, J. Tan
    CERN, Geneva, Switzerland
  • J. Golm, F. Schmidl, P. Seidel
    FSU Jena, Jena, Germany
  • J. Golm, T. Stöhlker, V. Tympel
    HIJ, Jena, Germany
  • M. Schmelz, R. Stolz, V. Zakosarenko
    IPHT, Jena, Germany
  • T. Stöhlker
    IOQ, 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. 05P15SJRBA.
The storage of low current beams as well as the long extraction times from the synchrotrons at FAIR require non-destructive beam intensity monitoring with a current resolution of nanoampere. To fulfill this requirement, the concept of the Cryogenic Current Comparator (CCC), based on the low temperature SQUID, is used to obtain an extremely sensitive beam current transformer. During the last years, CCCs have been installed to do measurements of the spill structure in the extraction line of GSI SIS18 and for current monitoring in the CERN Antiproton Decelerator. From these experiences lessons can be learned to facilitate further developments. The goal of the ongoing research is to improve the robustness of the CCC towards external influences, such as vibrations, stray fields and He-pressure variations, as well as to develop a cost-efficient concept for the superconducting shield and the cryostat.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC08  
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MOPC10 Upgrade and Improvement of CT Based on TMR 134
 
  • Y. Zhao, Y.Y. Du, L. Wang
    IHEP, Beijing, People's Republic of China
 
  The CT based on TMR sensor has been developed in the lab. For Improving the accuracy and linearity, re-ducing the influence of sensor position, a series simu-lation and calculation have been done which conduct an upgrade both in the mechanical structure and elec-tronics design. Lab test shows good results and test on beam will be carried on soon.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC10  
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