NSLSII Stability Review Close Out April 20 2007

NSLS-II Stability Review Close Out – April 20, 2007 Introduction R. Hettel User requirements R. Hettel Conventional construction J. Sidarous Mechanical systems J-R Chen Orbit feedback and controls C. Steier Electrical systems and instrumentation O. Singh RF systems J. Byrd

Charge to the Review Committee Have source stability requirements been sufficiently identified to address user requirements? Have requirements for conventional (and mechanical) construction been sufficiently identified to provide stable foundation, minimize vibrations (cultural, self-induced), provide thermal stability? What is best approach to design orbit feedback system? (integration of fast/slow, local feedback, photon monitors) Have power supply stability requirements been sufficiently identified? What is best approach for rf and photon BPM design? Have RF system requirements and implementation plan been sufficiently identified to address high-frequency stability?

Areas of Review Consideration • scope of topic sufficiently defined? • design requirements identified? • technical issues and risks identified? • sufficient design resources (tools, staff, etc)? • sufficient time? – critical path areas • areas of further study (and review)? • r&d plan identified?

User Stability Requirements Nominal specs (partial): • 300 -nm positional stability of special BPMs • 10% beam dimension stability is nominal target • vertical coupling set at diffraction limit @ 1 angstrom • 5 x 10 -5 energy stability Some specific user specs: • STXM – 0. 01% intensity stability (vertical position), 0. 01 Hz- 100 k. Hz – need I 0 measure after zone plate to normalize • 0. 1 me. V res for 9. 1 ke. V • IXS: vert angle <0. 25 urad • infrared: <1 um vert in bend, few hours-10 k. Hz • Switched EPU: 0. 25 urad canting angle, mechanical chopper • many more specs made at workshop – will include Working Group leader summaries in final report

User Stability Requirements from Report of Stability Task Force • specs already out-dated • needs to include intensity and energy requirements • all requirements should be specified as a function of frequency range • this effort needs to continue with much communication between beam line and accelerator experts

Comments on Stability Requirements • 10% orbit stability may not be enough for many applications: 5% or maybe less in some cases • Some users 0. 1 % intensity stability: need to translate to positional and beam size specification ( 0. 1% beam size stability) • All stability requirements need to be specified as function of frequency range • Is the changing vertical beam size in small-waist IDs accounted for in stability requirement? • What is the impact of coherence requirements on stability specs, and how do coherence effects influence beam position and/or energy measurement? • Switched EPU with mechanical chopper: systematic differences between fixed sources and very stringent BL alignment tolerances; hard to match source profiles– may end up using switched ID with subsequent stability requirements • Stabilization requirements for special applications should be divided between accelerator and beam lines – find ways to meet demanding specs assuming 0. 1 sigma accelerator stability (maybe 0. 2 sigma vertically)

Comments on Stability Solutions • Need cutting-edge technology in many systems on BL and in accelerator • May need mechanical motion/position survey sensors at critical points from source to experiment and in accelerator; ability to include sensors in feedback • Need to mechanically model critical beam line set-ups (supports, modes, etc) • Find a way to monitor I 0 just upstream of sample for all critical systems – normalization on sample-by-sample – but there are limits to quality of I 0 detector • Recommend phase space acceptance analysis projected to source phase space • Use “telescope technology” to maintain relative stability of components (e. g. D. Shu) • Need instrumentation infrastructure to verify accelerator vs. beam line stability issues and to help achieve stability goals • Committee strongly supports beam designer’s goal to consider source and beam line stability “holistically”

Other Comments Top-Off Injection • Need to specify impact of top-off transients on user beam stability • Some users will need to blank out data acquisition; need ability to gate injection transient. • Committee suggests that <<1% current constancy should be goal • What if top-off has safety problems? Is there room for permanent magnet deflectors on beam lines as a back-up solution to radiation safety issues? Diagnostic Beam Line(s) • 2 beam lines? : at low and high dispersion points energy spread, coupling, emittance testing devices, etc). • Should have very high resolution for vertical beam size/emittance • Could be shared with user beam lines