FY07 RHIC Schottky and Tune Ripple Experiments Plans

1
FY07 RHIC Schottky and Tune Ripple Experiments
Plans

• M. Blaskiewicz, K. Brown, D. Bruno, P. Cameron,
  C. Degen, A. Della Penna, W. Fischer,
  G. Ganetis, R. Lee, T. Russo, C. Schultheiss

2
Schottky Systems

• Low Frequency (LF) system (245 MHz)
• narrow line widths
• good resolution of synchrotron lines (ns
  measure)
• good resolution of coupling
• low Q system, signal levels for pp around 15 dB
  (at best) with gt5 dB noise background
• High Frequency (HF) system (2.07 GHz)
• large line widths
• clean signals (20-30 dB signal with lt1 dB noise)
• with proper fitting, good resolution of Q Q
• High Q system with HF (so low noise) lots of
  signal

3
Schottky Systems

• Traveling Wave (TW) system (1.70 GHz)
• line widths narrower than HF
• Purpose is to give bunch by bunch Tune data, and
  Schottky spectra (chrom., emittance, anything
  HF can do).
• Low Q system signal levels are lower than HF

4
TW Spectra Note not true Schottky
spectra Large Coherence in beam!
5
Parameters

• Basic parameters
• frev 78.13 - 78.196 kHz (protons)
• h 0.00182 at g 106.5
• dp/p 0.001 (w/o 200 MHz)

Parameter LF system HF system TW system
Freq. 245 MHz 2.07 GHz 1.70 GHz
n 3133 26473 21740
Line Widths 440 Hz 3700 Hz 3000 Hz
6
Schottky Plans

• LF
• New software analysis in manager
• Documentation!
• Data acquisition w/o labview
• control of mux from manager
• tracking through acceleration cycle
• HF
• Developing analysis into manager
• labview used only for data acquisition
• Working on methods to have it track though
  acceleration cycle
• emittance calibration

7
Schottky Plans

• TW
• data analysis in manager
• labview used only for data acquisition
• adding gating to get bunch by bunch spectra
• Move amplifiers into ring
• Still a lot of development new system

8
A few things I learned at FNAL

• Operators use dedicated scope on LF Schottky
  system no interest in TW system. They look at
  spectra!
• Tune space display program does not display tune
  spread! It shows tune measurements with
  persistence, and so shows amount of variation in
  tune over many measurements.
• High level of integration in application and data
  acquisition system to controls.

9
Tune Ripple
10
AC Quadrupole plans

• p.s. in 1004A, magnet is at 4 Oclock
• No Remote On/Off control. Still requires a
  person to turn on/off locally.
• Adding a function generator controllable from MCR
  for set-point (direct connection through
  ethernet).
• Local scope, temporary setup, will be connected
  via ethernet to be able to see voltage and
  current signals remotely.
• function generator and scope will reside on a
  cart next to the tune ripple p.s. There will be
  signs on the cart so everyone knows whose
  equipment it is and what it is for.
• System will still be able to be used for echo
  measurements by connecting cables to another p.s.

11
AC Quadrupole

• Based on magnetic measurements
• Where I is in kA, b in m, Br in Tm.
• At injection with /- 10 amp, DQ3x10-4
• On the Schottky spectra this is about 45 Hz.
• For LF Schottky this is not easily measurable
  (smaller than a line width). It is easily
  measurable with BBQ.

12
AC Quadrupole on /- 10 A at 50 Hz
AC Quadrupole off.
13
Comments on Emittance
14
Emittance calibration - the principle

• Simple
• Schottky pickup is moveable controllable beam
  offset
• Schottky signal is macro-particle of charge
  sqrt(N), where N is number of beam particles
• This macro-particle deposits power in the
  spectrum at both revolution and betatron
  frequencies
• Beam offset at which power in rev line equals
  power in betatron lines is the rms beam sigma
• But not so simple
• not able to correct for motion in pickup during
  calibration e.g. 10 Hz
• no dispersion correction

15
RHIC Schottky and IPM emittances
vertical planes recalibrated here
vertical scale is 95 emittance in mm-mrad (note
suppressed zero)
16
Schottky Experiments

• Lots of parasitic looking at signals.
• Comparisons of Schottky (HF/LF) tunes and tune
  spreads to other measurements.
• Understanding emittance measurements
• Understanding tune spread measurements
• Beam-beam effects? Gap-cleaning effects? Getting
  familiar with Au signals.

17
Tune Ripple Experiments

• BBQ system is key!
• AC Quadrupole is a reference calibration
• Systematic studies
• What does BBQ see with and without Booster
  pulsing?
• What does BBQ see with RHIC mains run from
  rectify p.s. on injection porch?
• What is contribution to tune ripple from
  different p.s.s? (is it measurable?)
• Look at difference in BBQ spectra for mistuned
  power supplies, compare line strengths to AC
  quadrupole pulse.
• Still working on details.

18
One more thing

• GMR CMR sensors.

19
Last Slide

• MOST THINGS you want to know about the beam are
  available (without perturbation!) in the Schottky
  spectrum, if you can figure out how to get it
  out.
• An emittance working group?
• Tune ripple measurements need good cooperation
  among many groups and will require significant
  time to work through and understand the BBQ
  measurements. Measurement need to be repeated. We
  dont always have all the control over what is
  happening, as much as we would like to believe!

20
Backup, Reference material,,,,
21
Standard References

• D. Boussard lectures http//preprints.cern.ch/cer
  nrep/1987/1987-003_v2/1987-003_v2.html
• R.Siemann USPAS lectures (1992S) Topics in
  Experimental Accelerator Physics
• W. Mackay USPAC lectures (2005S) Accelerator
  Physics Supplementary Notes
• D.A.Goldberg G.R. Lambertson Schottky Monitors
  for the Tevatron Collider, LBL internal tech.
  note no. BECON-61, LBID-1129

22
Line Locations and Widths

• Bunched beams each revolution line splits into
  an infinite number of synchrotron satellites
  separated by synchrotron frequency with
  amplitudes proportional to Bessel functions.

• Harmonic bands at nf0 with betatron bands split
  into pairs of sidebands at frequencies (m-q)f0
• Betatron sidebands have similar structure of
  synchrotron satellites

23
Line Locations and Widths

• Total line widths (bunched or unbunched)
• Individual Lines in bunched beam spectra

24
(No Transcript)