1 FermiLab Recycler Ring BPM Upgrade Based on Digital Receiver Technology R. Webber, J. Crisp, P. Prieto, D. Voy, C. Breigel, C. McClure, M. Mengel, S. Pordes

2 System Overview 1. Beam position split-plate capacitive pickups in the beamline vacuum. 2. Signal preamplifiers in the beam enclosure near the beamline. 3. Analog signal receiver (transition modules) and digital signal processing electronics in the service buildings. 4. Timing signal generators. 5. VME based “front-end” data acquisition and control computers and support hardware. 6. Integrated position and intensity calibration system. Pre-Amp GC-814 Software Position (A-B)/(A+B) * (-1)*Scale Factor + Offset B A A B Calibration

3 Signal Path FOR MORE INFO...

4 Dynamic Range Specifications Bunched Beam: 4 Bunches in successive 2.5 MHz RF buckets separated by 396 ns with sigma_t = 25ns to 50ns Intensity Range 2e10 to 30e10 particles total Un-Bunched Beam : Beam without modulation structure position for 20e10 to 400e10 stored particles Barrier Bucket Separation of 1824ns to 11172ns Absolute Position Measurement = +/- 1.0 mm +/ 5% Relative Position Measurement = +/- 0.4 mm +/- 5%

5 Signal Processing Modes 1) 2.5 MHz Ensemble-This mode measures the magnitude of the 2.5 MHz signal, the 4 bunch beam structure. 2) 2.5 MHz Bunch-by-Bunch-Measures the position of each of the four 2.5 MHz bunches. 3) 2.5 MHz Narrow Band-Measures the magnitude of the 2.5 MHz signal integrated over an interval corresponding to about 64 TBD Recycler turns. 4) Un-bunched Ensemble-This mode measures the magnitude of the signal from beam confined in a barrier bucket. 5) Un-bunched Head or Tail-This measures the position of the head and/or the tail of the barrier bucket structure beam. 6) 89 KHz Narrow Band-This mode measures the magnitude of the 89 KHz signal integrated over an interval corresponding to 32 Recycler turns).

6 VME vs. DMA Transfers

7 Signal Attenuation In Datalene Twisted Pair Multi-Conductor Cable Between Pre-Amp Output and Transition Module Input Signals with small sigma_t are attenuated more than larger sigm_t (50ns)

8 Frequency Response Measurements: Green trace: BPM plate terminated in 50 Ω Red Trace: BPM, PreAmp, and Transition Module

9 Un-Bunched Pbar Beam Digitized through DDC Board Displayed Using Engineering Page Fs = 80 MHz Display Range= +/ Fs = 80 MHz Display Range= +/

10 Engineering Page Display of Plate A and B I and Q Pair, Magnitude, Phase, Position, and Intensity

11 System Noise Contributions to Position Error

12 DDC Position vs Intensity Scan for 53 MHz 84 Bunches Using AWG Source and Switchable Attenuators Plotted as Measured Position vs. Intensity Calculated Position noise and Measured Position Noise vs Measured Intensity (70μVrms of A/D noise at Highest Intensity)

13 Recycler TBTBPM Measured Positions Fitted To Sine Function

14 Histogram of RMS Position Deviation For Vertical and Horizontal BPM’s