Almalki, M.

Baricevic, B.

Forck, P.

Hrovatin, R.

Kaufmann, W.

Kowina, P.

Krüger, C.

Singh, R.

Znidarcic, M.

GSI Repository

GSITemplate2007Test of Digital Electronics for the p-LINAC BPMs at UNILACM. Almalki1, P. Forck1, W. Kaufmann1, P. Kowina1, R.Singh1, C. Krüger1, B. Baricevic2, M. Znidarcic2, R. Hrovatin21GSI, Darmstadt, Germany; 2I-Tech, Solkan, SloveniaIntroductionFor the planned proton-LINAC at the FAIR facility [1], Beam Position Monitors (BPM) will be installed at 14 locations along the LINAC [2]. The digital signal pro-cessing to derive the transverse beam position and the beam velocity via time-of-flight determination could be implemented by so called Libera SPH (Libera Single Pass H Hadron) electronic from company I-Tech [2,3]. The specification for position measurement is 0.1 mm spatial resolution averaged over one 30 ms long macro pulse. For time-of-flight beam velocity determination an accuracy of 10 ps is required corresponding to a phase of1° with respect to 325 MHz acceleration frequency. A beam-based test was conducted at UNILAC to test the performance of Libera SPH electronics. For the same beam settings time-domain analogue signals were record-ed with a 20 GSa/s oscilloscope for comparison. These time-domain data were Fourier-transformed and com-pared to the frequency-domain data from the Libera SPH.Experimental Setup and First ResultsThe beam-based test was performed at UNILAC with aCa10+ beam at 1.4 MeV/u and a beam current of ~ 80 µA.Using a buncher cavity for longitudinal focusing, several bunch shapes with different amplitudes and width were generated. A single BPM was used as a Bunch Arrival Monitor to further characterize the dependence of beam arrival time on bunch shape. The arrival timeas depicted in Fig.1.Figure 1: Time-domain recording of single bunches for different buncher cavity amplitudes are depicted to de-termine the individual zero crossing points.The signals from a four plate BPM were sampled at 117.440 MSa/s with 16-bit ADC and digitally processed by Libera SPH unit to produce I and Q data stream for amplitude determination and phase calculation with re-spect to the 108.4 MHz acceleration frequecy. The RF analogue front-end of Libera SPH unit was customizedfor UNILAC parameters to perform the frequency-domain evaluation at the first two harmonics (108.4 MHz & 216.8 MHz). Using an amplification of 44 dB, the input peak voltages for seven bunch shapes recorded by LiberaSPH were in the range of 0.57 V to 1.05 V.As depicted in Fig. 2 the evaluated results showed some agreement between the Libera SPH phase readingsand the time-domain measurements. Furthermore, Libera SPH processed the larger amplitude signals with a resolu-tion of less than However, the FFT calculations of the single bunch data and the bunch stream are better matched to the time-domain evaluation.Figure 2: Time-domain data versus Libera SPH and FFT calculations for a single bunch and a stream of 30000 bunches.Summary and OutlookThe tbeam position but for phase detection it does not fulfil the requirements yet. However, modifica-tions might lead to the desired accuracy. Therefore, fur-ther investigations are planned to improve the perfor-mance based on a comprehensive modelling of the digital signal processing algorithm. References[1] Report , March 2009.https://edms.cern.ch/document/994418/1[2]FAIR Proton-[3] www.i-tech.si-2 0 2 4 6-0.500.511.5Time (ns)Amplitude (V)  Bunch 1Bunch 2Bunch 3Bunch 4Bunch 5Bunch 6Bunch 7Zero Crossing Pointsreference-20 -10 0 10 20-25-20-15-10-50510152025                 Zero Crossing tz     ( Degree @ 108MHz )Phase [Libera SPH & FFT calculations] (Degree)  FFT for a streamFFT for a single bunchLibera SPHGSI SCIENTIFIC REPORT 2012 PHN-FAIR-03FAIR@GSI 227

Test of Digital Electronics for the p-LINAC BPMs at UNILAC

http://repository.gsi.de/record/52126/files/PHN-FAIR-03.pdf

Test of Digital Electronics for the p-LINAC BPMs at UNILAC

Abstract

Similar works

Full text

Available Versions

GSI Repository