# Presentation: 507186

## Tevatron Software Digital Receiver Beam Line Tuner

- Vic Scarpine
- Instrumentation
- Instrumentation Meeting
- July 13, 2005

## Introduction

- Primary function of a Beam Line Tuner (BLT) is to measure turn-by-turn transverse beam positions for all bunches during transfers from one accelerator ring to another
- Can measure betatron oscillations, fractional tune, coupling, time-of-arrival, synchrotron oscillations, emittance growth, etc
- Focus has been on betatron measurements for improved closing
- Feed-forward correction system – correct magnets for next transfer
*BLT is a key component for reducing transverse emittances and increase luminosity*

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Tevatron BLT

- Measure all proton and pbar transfers from Main Injector to Tevatron
- Requirements:
- Measure initial injection oscillations for every proton and pbar bunch
- Measure tunes, emittance growth, synchrotron frequency
- Measure bunch time-of-arrival relative to RF
- Beam formats:
- Pbar:
- Four 53 MHz bunches separated by 392 ns at 150 GeV
- Protons:
- Single 53 MHz bunch at 150 GeV

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Basic BLT System

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Analog Signals - Striplines and Fanout

- TeV Stripline Parameters:
- ~ 30 dB directionality
- 1 meter long (<  1/4 )
- D = 83 mm
- 0.65 dB/mm Sensitivity
- Located at near F0
- Optimally separated proton and pbars
- Fanout Box
- M/A-Com H-9 Junction Hybrid generates A+B and A-B

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Tevatron Scope BLT

- Use Tektronix TDS7104 as fast waveform digitizer
- 2.5 GSample/sec/channel
- Segmented memory
- Embedded PC/Windows
- Samples pbar bunches each transfer
- Signal processing analysis of waveform in Scope PC
- Decimate data to single position per bunch
- Pbars – 64 turns
- Too slow for protons
- Only used for closing pbars

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Tevatron Software Digital Receiver BLT

- Software Digital Receiver system for pbars (similar for protons)
- 30 MHz LP to ring single 53 MHz bunch
- Digitize bunches at 2*RF
- Transfer digital data to PC
- Down convert at 30 MHz
- Correlate with window function
- Correlation max gives A and B
- Generate position and time-of-arrival for ~ 1000 turns

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Tev BLT Trigger

- UCD VXI trigger module
- Use TCLK and BSCLK to trigger pattern generator turn-by-turn at injection
- Use pattern generator to gate Struck digitizing card for injected proton or pbar bunches

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Tev BLT Digitizer

- Struck SIS3300 Digitizing card
- 8 ADC channels per board
- 12 bit ADCs
- Digitizing clock at 106 MHz (2*RF)
- 128K samples per channel
- 128 sample per turn for 1024 turns
- 4 x 32 sample per pbar bunch (~ 320 ns window for each pbar bunch)
- 30 MHz signal damps out in ~150 ns

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Analog Signals

- 53 MHz signal too short for 106 MHz digitizer
- Stretch signal using 30 MHz low-pass filter

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Down Conversion

- Down convert digitized signal

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Windows for Convolution

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Convolution

- Use peak of each convolution bump for A and B values

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Store 4175 Proton Vertical Oscillations

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Store 4175 Proton Horizontal Oscillations

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Store 4175 Injections Oscillations

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Store 4210 Pbar Injections

- Why is 4th bunch different closed orbit than first three bunches?
- (Of course it can’t be!)

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Proton Contamination on Pbars

- Two effects:
- Proton reflection 600 ns later falls on pbar bunch (except for last pbar)
- Proton signal generates some sort of structured reflection in pbar signal
- Fix: Add 10 db attenuators at stripline on proton signal cables

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Pbar Oscillations after Attenuators

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Pbar Fractional Tunes

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Pbar Time of Arrival Relative to RF

- Use real and imaginary portions of convolution to determine phase of bunch relative to RF
- 	T = 1/(2f)*atan(Imag/Real)

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

## Summary

- Tevatron software Digital Receiver BLT measuring turn-by-turn transverse positions for all proton and pbar bunches for each shot for 1000 turns
- Position information being used for emittance growth estimates
- BLT also determining bunch time-of-arrival relative to RF
- Presently system only used for time-of-arrival information
- Want to use system to close on protons (and possible close on pbars)

- Instrumentation Meeting - TeV  BLT

- July 13, 2005

- Instrumentation Meeting - TeV  BLT

- July 13, 2005