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

Schottky Systems Low Frequency (LF) system (245 MHz) narrow line widths good resolution of synchrotron lines ( s measure) good resolution of coupling low Q system, signal levels for pp around 15 dB (at best) with >5 dB noise background High Frequency (HF) system (2.07 GHz) large line widths clean signals (20-30 dB signal with <1 dB noise) with proper fitting, good resolution of Q & Q’ High Q system with HF (so low noise); lots of signal

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

TW Spectra: Note = not true Schottky spectra Large Coherence in beam!

Parameters Basic parameters f rev = kHz (protons)  = at  = dp/p ~ (w/o 200 MHz) ParameterLF systemHF systemTW system Freq.245 MHz2.07 GHz1.70 GHz n~3133~26473~21740 Line Widths~440 Hz~3700 Hz~3000 Hz

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

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

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.

Tune Ripple

AC Quadrupole plans p.s. in 1004A, magnet is at 4 O’clock 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.

AC Quadrupole Based on magnetic measurements Where I is in kA,  in m, B  in Tm. At injection with +/- 10 amp,  Q~3x10 -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.

AC Quadrupole off. AC Quadrupole on +/- 10 A at 50 Hz

Comments on Emittance

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

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

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.

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.

One more thing … GMR & CMR sensors.

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 don’t always have all the control over what is happening, as much as we would like to believe!

Backup, Reference material,,,,

Standard References D. Boussard lectures : 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

Line Locations and Widths Harmonic bands at nf 0 with betatron bands split into pairs of sidebands at frequencies (m+-q)f 0 Betatron sidebands have similar structure of synchrotron satellites Bunched beams: each revolution line splits into an infinite number of synchrotron satellites separated by synchrotron frequency with amplitudes proportional to Bessel functions.

Line Locations and Widths Total line widths (bunched or unbunched) Individual Lines in bunched beam spectra