LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 1 Michigan Group NSF Proposal Richard Gustafson, Keith Riles University of Michigan LIGO Program Advisory Committee Meeting Livingston, Louisiana December 5-6, 2002

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 2 Detector Characterization »Leadership »Organization of LSC participation in data runs »Online, real-time diagnostic & characterization software »Noise and pathology investigation Search for Periodic Sources of Gravitational Waves »Active contributors to Periodic Upper Limits Group (PULG) »Focussed on “unbiased” (less sensitive) search over entire sky »Identification of instrumental lines with frequency modulations Overview of Activities

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 3 Commissioning & Detector Advancement »Instrumental diagnostics »RF & digitization noise investigations »Alternative servo control error signals for robust diagnostics / locking Advanced LIGO »Servo controls development Michigan Group Members Ph.D.’s:Richard Gustafson, Keith Riles Graduate student: Dave Chin Undergraduate:Michael La Marca Programmer / future Graduate Student:Vladimir Dergachev Overview of Activities

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 4 LSC Detector Characterization Working Group (Chair: K. Riles, Lab Liaison: D. Sigg – LHO) Working Group Functions: Provide online, real-time diagnostics in control room Record instrumental/environmental transients and performance trends Investigations of noise sources and pathologies in data runs Calibration and data quality information for data runs Data set reduction Staffing of scientific monitoring shifts during data runs Miscellaneous related administrative duties (Riles) Meetings (organizing, hosting, writing minutes), liaison to other groups, reporting to NSF panels, author on analysis white paper Detector Characterization

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 5 Detector Characterization Data Run Activities (organized by Riles) Staffing of scientific monitoring shifts in data runs: »Monitoring of data – Detecting pathologies »Decisions on running mode & control parameter adjustments »Sample S1 “scimon” shift listSample S1 “scimon” shift list Investigations: »Typically ~dozen teams formed for each run (E2-E7, S1) »Sample topics of study: calibration, data quality, lock losses, glitches, inter-channel correlations,bilinear noise, data set reduction, timing precision, line noise, signal injection, »Investigation reports given at regular DetChar telecons & at bi-annual LSC meetings

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 6 Detector Characterization Direct Michigan participation in data run investigations (Chin, Dergachev, Gustafson, Riles) Past: Led Lock Loss Team for E2, E3, E4, E5 runs »Identified saturations & other pathologies »Quantified severity of LLO seismic noise (see figure) Provided data quality info for E2-E7 runs Contributor to S1 Data Quality Team Wrote offline trend viewer with remote access to site data Future: Spectral distortion (monitoring) Servo instabilities / drifts (modelling ) Upgrade trend viewer as site bandwidth increases

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 7 Seismic Impact at LLO in E4 Seismic noise over the 3-day run Resulting lock livetime fraction

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 8 Detector Characterization Michigan Contributions to Online Diagnostics (Chin, Riles) Operational State Conditions: General-purpose interferometer state conditions used by many online Data Monitoring Tool (DMT) programs Supports arbitrary, run-time Boolean combinations of conditions LockLoss Monitoring Program (DMT) Provides graphic display of interferometer state vector history, cumulative livetime, database triggers, permanent record of all lock transitions Mature program – essential in data runs

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 9 Detector Characterization Michigan Contributions to Online Diagnostics (cont.) ServoMon Monitoring Program (DMT) Monitors sudden increases in spectral noise (violin modes, gain peaking, etc.) with alarms, database triggers, trends Useful now but needs refinement Planned enhancement: GW servo modelling with spectral prediction

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 10 Search for CW Sources The Michigan group analysis focus is the search for Continuous Wave (CW) Sources of Gravitational Waves (Chin, Dergachev, Gustafson, Riles) Now contributing members of PULG Prior to PULG formation wrote general-purpose antenna pattern analysis code for LIGO Analysis Library (LAL) under aegis of A.S.I.S. W.G.  Code now used by several analysis groups Have only recently begun intensive work on CW analysis  Ph.D. dissertation topic for Chin

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 11 Search for CW Sources Most promising periodic source: Rotating Neutron Stars (e.g., pulsar) But radiation requires an asymmetry or perturbation: Equatorial ellipticity (e.g., – mm-high “mountain”): h α ε equat Poloidal ellipticity (natural) + wobble angle: h α ε pol x Θ wobble (precession due to different L and Ω axes) Serious technical difficulty: Doppler frequency shifts (see figure) »Frequency modulation from earth’s rotation (v/c ~ ) »Frequency modulation from earth’s orbital motion (v/c ~ ) Additional, related complications: »Daily amplitude modulation of antenna pattern (sensitivity) »Spin-down of source »Orbital motion of sources in binary systems

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 12 Search for CW Sources Modulations / drifts complicate analysis enormously: »Simple Fourier transform inadequate »Every sky direction requires different demodulation  All-sky survey at full sensitivity is formidable computing challenge Standard deviation in  f/f (x10 6 ) vs RA & declination (S1 data run)

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 13 Search for CW Sources Michigan focus – “Unbiased” all-sky search for CW flux: (based on incoherent averaging, i.e., less sensitive approach) First iteration – Brute force: Measure power in selected bins of averaged periodograms Bins defined by source parameters (f, RA,  ) Estimate noise level & statistics from neighboring bins Set upper limit on quasi-sinusoidal signal on top of empirically determined noise Scale upper limit by antenna pattern correction Quasi-analytic method, anchored in Monte Carlo simulation

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 14 Search for CW Sources Disadvantages of brute-force approach: Intrinsic sensitivity suffers; depends on sky direction Detector non-stationarity especially harmful to sensitivity Advantages: Computationally tractable Robust against uncertainties in source parameters First look at S1 data: Highly non-stationary (see figures) Exploring data segment vetoes and reweighting schemes Focussing on “playground frequency band” near 660 Hz

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 15 Search for CW Sources Statistical measures of noise in narrow band for > second DFT’s (LLO data from S1) Plotted vs time during run:Ordered by least variance

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 16 Search for CW Sources Diminishing returns on total variance after ~100 DFT’s

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 17 Search for CW Sources Immediate plan: Complete present brute-force analysis with only modest refinements Aim: Inclusion in first upper limits publication on periodic sources Longer term: More sophisticated, time-dependent search over frequency bins (similar to “stack-slide” method of Brady et al.) Inclusion of varying source parameters, including binary orbital motion Explore more exotic “periodic glitch” sources

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 18 Commissioning & Detector Advancement We’ve worked with LHO staff and CIT/MIT commissioners to Bring interferometers into operation Reduce noise Evolve the operations procedures Understand operational reality Develop new ideas

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 19 Commissioning & Detector Advancement Some Michigan contributions: 2Ώ scheme of monitoring recycling cavity sideband (SB) buildup (with W. Kells from the 40-Meter experience) 2Ώ demod hardware for deriving SB power signal for lock acquisition Assistance in evolving the lock acquisition with M. Evans & other IFO scientists Identification / fix of gross RF leakage contamination problem Identification / fix of gross 60 Hz ground noise problem Invention of AM-based l+ / l- servo scheme: (more later) »Used on fully recycled 40 Meter »Tested on 2-km IFO power recycled cavity – Full lock expected soon Found new clean way to derive AM second SB for AM 40 MHz

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 20 Commissioning & Detector Advancement Some Michigan contributions: (continued) Early study of Pentec ADC/DAC problems: »Gross phase noise  massive down conversion »Programming subtleties Temperature trouble elucidated: Pentiums shut down when too hot (!) “Hop test” for alignment »Reflected beam spot must not hop when arm on/off »Devised at 40 meter

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 21 The AM Servo for l+, l- Degrees of Freedom Standard LIGO length error signals derived by comparing phase shift of carrier in a cavity with RF sidebands (Pound-Drever-Hall). One serves as local oscillator for the other. Works well in arms, but in recycled Michelson cavity the carrier signal info contains arm errors in addition to local cavity error. Hierarchical servos make a miracle happen, but lock acquisition challenging and fragile We asked: Why not add a 2 nd virgin (non-resonant, non-phase-shifted) SB to beat against the first for l+, l- servos?

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 22 The AM Servo for l+, l- Degrees of Freedom Used at the 40 Meter: Quick, long, robust locks Have started on the LHO 2-km: Power recycled Michelson (no arms) works robustly Full lock to be attempted soon Expect quick, robust locking Noise character unknown – will be measured

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 23 Future Commissioning: More of the Above Help drive IFO’s from m/Hz 1/2 to m/Hz 1/2  It’s getting harder to improve! Many proposal bullets well underway (by us and other IFO scientists) Study the DAC/ADC noise with new digital suspension controllers  Explore issues at –60 db below 1 bit; relevant to CW search Devise on-line monitors of digital aspects of servo noise Explore alignment/clipping of the output beams and devise diagnostics short of opening / resurveying (work in progress)

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 24 Future Commissioning Demonstrate Full Lock of LHO Interferometers with AM l+ l- servo Expect immediate lock acquisition Noise issues not so clear Develop compound alignment knobs; rotate “aligned” arm about a point  “Software knobs” Pursue more subtle forms of 60 Hz and its harmonics

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 25 Advanced LIGO – New Servo Schema: Dither Lock We propose to explore dither modulation of arms and cavities, effected by driving a test mass mirror at a resonant frequency, e.g., N x 15 kHz We locked a 40-meter arm by dither lock (low frequency) 15 kHz x 4 = 50 kHz might be far enough out of LIGO ban to operate Advantages: Handles any power level Allows independent error signals for different cavities Possibly no Schnupp asymmetry operation  better contrast Noise issues to be explored

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 26 Summary Group is active: Detector characterization Search for periodic sources Commissioning IFO servo control development Have voted with our feet to make LIGO succeed: Committed to success of instrument Carrying out astrophysical analysis Have made good use of resources – including undergraduates

LIGO-G020XXX-00-Z Michigan Group NSF Proposal - 12/6/02R. Gustafson, K. Riles - University of Michigan 27 Summary Request: Continued funding PLUS postdoc and 2 nd graduate student Plan: Station postdoc and student at Hanford Find gravity waves !