Bräuning, H.

Chorniy, O.

Miedzik, P. B.

Reiter, A.

GSI Repository

Bunch tomography for longitudinal diagnostics at FAIRO. Chorniy, H.Bra¨uning, P.Miedzik, A.ReiterGSI, Darmstadt, GermanyThe longitudinal diagnostics is an important tool to ob-serve the beam behaviour under various RF gymnastic pro-cesses in FAIR rings. After installation of a dedicatedFESA based data acquisition (DAQ) system for bunch mea-surements [1] the software and hardware parts were ex-panded providing the ability to perform the on-line bunchtomography. Presently, the system is under further deve-lopments which includes fine tuning of the GUI, debuggingof the FESA class and final assembling of the electronics.On-line bunch tomographyTomographic reconstruction of longitudinal phase spaceis a reliable instrument in bunched beam diagnostic [2].At GSI, the first simple on-line tool was realized [1] usingMathematica software and the tomography code. Measure-ments in the SIS18 were done using the sum signal of asingle BPM. The Lecroy oscilloscope was used as DAQ. Itwas required to preview signal in a form of a waterfall plotand to choose different important parameters for tomogra-phy. For this purposes a test GUI in Mathematica was writ-ten. The tomographic reconstruction itself was done usinga FORTRAN based code written at CERN [2].After installation of the broadband FCT, the aim was toimplement the tomography tool into the new FCT DAQdescribed below. First tests were performed in a ”quasion-line” regime which means the signal source was signalgenerator, the timing source was in-house developed timingsimulator. A snapshot of the GUI is shown in Figure 1.Figure 1: GUI with reconstructed phase space.Temporarily, the tomography code resides on the PCwhere the GUI runs. It is planned to use a dedicated PCwith a multi-core CPU in order to accelerate the reconstruc-tion process. A more advanced option is to consider a GPUbased tomography, while a speedup of 10-100 times can beachieved in comparison to a CPU. In addition, this optionwill require the development of a new tomography code.DAQ system for bunch diagnosticsIn parallel to the feasibility study of tomography the on-line system for the diagnostics using FCT was developed.This system consists of the FAIR specified VME basedDAQ with FESA framework based software and Java GUI.The system was successfully tested in 2012 [3].The length of the synchrotron cycle can ranges up to se-veral seconds. At high sampling rates it will lead to a largeamount of raw data. Data reduction can be achieved bytriggering the DAQ system on a rate divider output to whichthe RF master oscillator is connected.Previously the data reduction was realized using NIMmodules. A new FPGA based single board electronics cardcovering multiple-event functionality including the timingreceiver was designed, tested and will be assembled. Theboard is shown in Fig.2.Figure 2: FPGA based single board electronics (right) formultiple-events triggering to replace NIM based solution(left).References[1] O. Chorniy, H. Bra¨uning, T. Hoffmann, H. Reeg, A. Reiter,”A FESA DAQ for Fast Current Transformer in SIS 18”,IBIC2013, Oxford, September 2013[2] S. Hancock, P. Knaus, M. Lindroos, Tomographic measure-ments of longitudinal phase space density, EPAC98.[3] O. Chorniy, H. Bra¨uning, T. Hoffmann, H. Reeg, A. Reiter,M. Witthaus, ”New Data Acquisition for Beam Transformersin SIS18 and Transfer Lines”, GSI Scientific Report 2013FG-UNILAC-17 GSI SCIENTIFIC REPORT 2014412 DOI:10.15120/GR-2015-1-FG-UNILAC-17

Bunch tomography for longitudinal diagnostics at FAIR

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Bunch tomography for longitudinal diagnostics at FAIR

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