APEX Cameron BBQ 3Nov06 BBQ and Other Developments Peter Cameron

APEX Cameron BBQ 3Nov06 Outline 60Hz harmonics - covered yesterday Chromaticity measurement/feedback –slow (1Hz) radial modulation – the baseline –slow ( >fs) phase modulation –multitone –continuous head-tail e-cloud tune shift along the bunch Central frequency measurement –two parameters – non-lin chrom and momentum offset BTF –optimize (Wolfram) –BBTF for lumi,… Monopole squid

APEX Cameron BBQ 3Nov06 Chromaticity Measurement and Feedback Chrom feedback – the final step in ramp ‘automation’? “Present measurement quality is questionable” – AD et al Possible alternative techniques for continuous measurement (desirable for feedback) –phase modulation (SPS, Tevatron, RHIC) advantage - does not stress tune tracker (mod freq beyond PLL BW) disadvantages – frequency must avoid synchrotron frequency, possible beam loss, not clear S/N is better than slow radial –3 tone method (Hermann’s suggestion – 100 tone) (SPS, RHIC?) advantage – no momentum perturbation disadvantages – additional excitation/emittance growth, complication of synchrotron satellites, requires knowledge of eta, bunch length,… –continuous head-tail (SPS, Tevatron, RHIC) advantage – no momentum perturbation disadvantage – no proper theoretical understanding (yet)

APEX Cameron BBQ 3Nov06 Summary of Chromaticity tt tt vert horiz dp/p of +/ gives ~+/-100  radial modulation (RHIC&LHC) Q' ramp 6380 ramp 6382 ramp 6381 in RHIC modulation is at 1Hz chrom - good results under sequencer control

APEX Cameron BBQ 3Nov06 Chromaticity Measurement and Feedback Chrom feedback – the final step in ramp ‘automation’? “Present measurement quality is questionable” – AD et al Possible alternative techniques for continuous measurement (desirable for feedback) –phase modulation (SPS, Tevatron, RHIC) advantage - does not stress tune tracker (mod freq beyond PLL BW) disadvantages – limited to <~1/2 synchrotron frequency, possible beam loss, not clear S/N is better than slow radial –3 tone method (Hermann’s suggestion – 100 tone) (SPS, RHIC?) advantage – no momentum perturbation disadvantages – additional excitation/emittance growth, complication of synchrotron satellites, requires knowledge of eta, bunch length,… –continuous head-tail (SPS, Tevatron, RHIC) advantage – no momentum perturbation disadvantage – no proper theoretical understanding (yet)

APEX Cameron BBQ 3Nov06 SPS testing Sep 2006 courtesy Ralph Steinhagen

APEX Cameron BBQ 3Nov06 so far – S/N poor for comparatively large dp/p

APEX Cameron BBQ 3Nov06 Chromaticity Measurement and Feedback Chrom feedback – the final step in ramp ‘automation’? “Present measurement quality is questionable” – AD et al Possible alternative techniques for continuous measurement (desirable for feedback) –phase modulation (SPS, Tevatron, RHIC) advantage - does not stress tune tracker (mod freq beyond PLL BW) disadvantages – limited to <~1/2 synchrotron frequency, possible beam loss, not clear S/N is better than slow radial –3 tone method (Hermann’s suggestion – 100 tone) (SPS, RHIC?) advantage – no momentum perturbation disadvantages – additional excitation/emittance growth, complication of synchrotron satellites, requires knowledge of eta, bunch length,… –continuous head-tail (SPS, Tevatron, RHIC) advantage – no momentum perturbation disadvantage – no proper theoretical understanding (yet)

APEX Cameron BBQ 3Nov06 courtesy C.Y. Tan

APEX Cameron BBQ 3Nov06 courtesy C.Y. Tan

APEX Cameron BBQ 3Nov06 Multi-tone method Recent (yesterday) results from SPS –3 tones – central lock plus 2 side tones –same kicker power at all 3 lines –40Hz offset –PLL BW 20 Hz –fs ~100Hz to 200Hz –general statement - “good results” - no quantitative data yet Difficult to implement at RHIC –varying synchrotron frequency on ramp, as low as ~10Hz at transition –PLL BW ~10Hz –just the same, it is worth studying, especially in light of…… Hermann’s suggestion – 10 tone? 100 tone? –3D AFE gives headroom on S/N before emittance growth becomes an issue –with FPGA-based BBQ it becomes somewhat trivial (at least from hardware/software point-of-view) to lock MANY loops on the beam –starts to look more like continuous BTF

APEX Cameron BBQ 3Nov06 Chromaticity Measurement and Feedback Chrom feedback – the final step in ramp ‘automation’? “Present measurement quality is questionable” – AD et al Possible alternative techniques for continuous measurement (desirable for feedback) –phase modulation (SPS, Tevatron, RHIC) advantage - does not stress tune tracker (mod freq beyond PLL BW) disadvantages – limited to <~1/2 synchrotron frequency, possible beam loss, not clear S/N is better than slow radial –3 tone method (Hermann’s suggestion – 100 tone) (SPS, RHIC?) advantage – no momentum perturbation disadvantages – additional excitation/emittance growth, complication of synchrotron satellites, requires knowledge of eta, bunch length,… –continuous head-tail (SPS, Tevatron, RHIC) advantage – no momentum perturbation disadvantage – no proper theoretical understanding (yet)

APEX Cameron BBQ 3Nov06 continuous head-tail

APEX Cameron BBQ 3Nov06 Rhodri Jones – continuous head tail 500 turn simulation results, phase difference between head and tail (settling time evident)

APEX Cameron BBQ 3Nov06 head tail     lowpass filtered head x tail 1 second mean =.758 mean =.283 February 2006 RHIC Run 6 - continuous head-tail chromaticity measurement using BBQ (no momentum perturbation) Marek and Rhodri

APEX Cameron BBQ 3Nov06 Chromaticity Measurement and Feedback Chrom feedback – the final step in ramp ‘automation’? “Present measurement quality is questionable” – AD et al Possible alternative techniques for continuous measurement (desirable for feedback) –phase modulation (SPS, Tevatron, RHIC) advantage - does not stress tune tracker (mod freq beyond PLL BW) disadvantages – limited to <~1/2 synchrotron frequency, possible beam loss, not clear S/N is better than slow radial –3 tone method (Hermann’s suggestion – 100 tone) (SPS, RHIC?) advantage – no momentum perturbation disadvantages – additional excitation/emittance growth, complication of synchrotron satellites, requires knowledge of eta, bunch length,… –continuous head-tail (SPS, Tevatron, RHIC) advantage – no momentum perturbation disadvantages –no proper theoretical understanding (yet – effort at both CERN and FNAL) –RHIC results not repeated at SPS Marek is working on improved detector

APEX Cameron BBQ 3Nov06 Outline 60Hz harmonics - covered yesterday Chromaticity measurement/feedback –slow (1Hz) radial modulation – the baseline –slow ( >fs) phase modulation –multitone –continuous head-tail e-cloud tune shift along the bunch – use 3D AFE? Central frequency measurement –two parameters – non-lin chrom and momentum offset BTF –optimize (Wolfram) –BBTF for lumi,… Monopole squid

APEX Cameron BBQ 3Nov06 Outline 60Hz harmonics - covered yesterday Chromaticity measurement/feedback –slow (1Hz) radial modulation – the baseline –slow ( >fs) phase modulation –multitone –continuous head-tail e-cloud tune shift along the bunch Central frequency measurement –‘two’ parameters – non-linearities and momentum offset BTF –optimize (Wolfram) –BBTF for lumi,… Monopole squid

APEX Cameron BBQ 3Nov06 Tune spread measurement methods Sliding window fit to response to Artus kick gives amplitude dependence of coherent tune Schottky – difficult to get needed resolution (upper  width + lower  width) - (2 x rev width) gives tune spread due to octupole and higher, (plus beam-beam,…) Zoomed Schottky width of central line of incoherent betatron distribution gives tune spread due to all contributions (sextupole, octupole, beam-beam,…) Central Frequency - all contributions from 23 Jan 04 BMX meeting

APEX Cameron BBQ 3Nov06 LF Schottky at Injection chrom = (lower - upper) / dp/p tune spread = (lower + upper) - (2 x rev) gives tune spread due to octupole and higher, (plus beam-beam,…)

APEX Cameron BBQ 3Nov06 zoomed HF Schottky - revolution line At store with storage RF on central line ‘infinitely narrow’ Synchrotron freq ~ 250Hz

APEX Cameron BBQ 3Nov06 LF Schottky at injection - 9 Dec 03 BH ~ 41 Hz ~.0005 BV ~ 29 Hz ~.0003 YH ~ 81 Hz ~.001 YV ~ 30 Hz ~.0003

APEX Cameron BBQ 3Nov06

Data from Dec 03 RHIC BMX Max beam lifetime was not at central frequency At that time not obvious how to improve RHIC performance using this measurement Steve Tepikian presentation a few weeks ago effect of NL chrom on tune footprint, beta fcns,… suggests why CF not optimal A possible relatively simple APEX: two knobs – amount beam is off-momentum, and non-lin corrector strength explore this parameter space for beam lifetime

APEX Cameron BBQ 3Nov06 Outline 60Hz harmonics - covered yesterday Chromaticity measurement/feedback –slow (1Hz) radial modulation – the baseline –slow ( >fs) phase modulation –multitone –continuous head-tail e-cloud tune shift along the bunch Central frequency measurement –‘two’ parameters – non-linearities and momentum offset BTF –optimize (Wolfram) –BBTF for lumi,… Monopole squid

APEX Cameron BBQ 3Nov06 Monopole squid just a heads up squid based monopole detector proposed to PAC by Chaudhari et al committee recommendation was to get experience with squid in RHIC IP radiation environment – concern is spurious radiation-induced quantum flux jumps test installation is in preparation for IP10 will need ~1hr access at start of APEX to transfer helium to the dewar