FY07 RHIC Schottky and FY07 RHIC Schottky and Tune Ripple Tune Ripple

Experiments PlansExperiments PlansM. Blaskiewicz, K. Brown, D. Bruno, P. M. Blaskiewicz, K. Brown, D. Bruno, P.

Cameron, C. Degen, A. Della Penna, W. Cameron, C. Degen, A. Della Penna, W. Fischer, G. Ganetis, R. Lee, T. Fischer, G. Ganetis, R. Lee, T.

Russo, C. Schultheiss Russo, C. Schultheiss

Schottky SystemsLow 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 backgroundHigh 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 SystemsTraveling 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!

ParametersBasic parameters

frev= 78.13 - 78.196 kHz (protons)= 0.00182 at = 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 GHzn ~3133 ~26473 ~21740Line Widths ~440 Hz ~3700 Hz ~3000 Hz

Schottky PlansLF New software – analysis in manager Documentation! Data acquisition w/o labview control of mux from manager tracking through acceleration cycleHF Developing analysis into manager labview used only for data acquisition Working on methods to have it track

though acceleration cycle emittance calibration

Schottky PlansTW 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 plansp.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 QuadrupoleBased 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.

B

IsdsB

sBsQ yx)(2895.0)()(

41

,

AC Quadrupole off.

AC Quadrupole on +/- 10 A at 50 Hz

Comments on Emittance

EmittanceEmittance calibration - the calibration - the principleprincipleSimple 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 RHIC Schottky and IPM emittances 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 measurementsBeam-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 SlideMOST 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 ReferencesD. Boussard lectures: http://preprints.cern.ch/cernrep/1987/1987-003_v2/1987-003_v2.html

R.Siemann USPAS lectures: (1992S) Topics in Experimental Accelerator PhysicsW. Mackay USPAC lectures: (2005S) Accelerator Physics Supplementary NotesD.A.Goldberg & G.R. Lambertson: Schottky Monitors for the Tevatron Collider, LBL internal tech. note no. BECON-61, LBID-1129

Line Locations and Widths

iis ptpQqnj

pipin eQqnJaefd 0/

00 ˆ/Re

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

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 WidthsTotal line widths (bunched or unbunched)

Individual Lines in bunched beam spectra

alLongitudin 0 ppfnf

Transverse 0 ppfqnf

allongitudinin width line Central 0|| randomff

beam)by filled isbucket RFfraction on (dependent nsoscillation synchrotro

linear-non toduefrequency n synchrotro of spread

allongitudinin width line satellite th0||||

s

s

f

fff

sfff

Q

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spread. tunebeam-beam ns,oscillatiobetatron linear -non todue is

Transversein width line Central