Review of 40m upgrade goals æ The primary goal of the 40 m upgrade is to demonstrate a scheme for using resonant sideband extraction èrseè, in either

Transcription

1 40m Upgrade Plans PRELIMINARY! æ Review of 40m upgrade goals æ 40m infrastructure upgrade æ RSE conæguration - design considerations æ IFO optical conæguration æ RSE control scheme æ people, money, schedule æ problems and questions A. Weinstein 40m upgrade LSC, LLO, 3è17è00 1

2 Review of 40m upgrade goals æ The primary goal of the 40 m upgrade is to demonstrate a scheme for using resonant sideband extraction èrseè, in either broadband or tuned conæg, appropriate for an optimal LIGO conæg æ RSE and DR have been demonstrated at Garching 30m, and at table-top IFOs æ An RSEèDR conæg appropriate for LIGO will be demonstrated at the Glasgow 10m æ For LIGO, need a full engineering prototype, using LIGO electronics and control scheme. This is the primary goal of the 40 m upgrade. æ Complements work at other R&D facilities: í 40m will focus on shot èphase, sensingè noise, high-f í LASTI: full-scale SEI,SUS prototyping; low-f í TNI: thermal noise; middle-f í ETF: Sagnac, high powered lasers A. Weinstein 40m upgrade LSC, LLO, 3è17è00 2

3 Secondary 40m upgrade goals Prototype ëeverything"? æ potentially, multiple pendula SUS this may be necessary, to extrapolate experience gained at 40m to LIGO-II æ potentially, advanced SEI systems scaled down, of course. Cannot replace full-scale testing at LASTI. æ LIGO-III: cryogenic TMs, QND, etc.. æ physicist training At the least, must prototype everything that has large impact on electronicsècontrol system, for a meaningful full engineering test! A. Weinstein 40m upgrade LSC, LLO, 3è17è00 3

4 40m infrastructure upgrade æ LIGO-like upgrade, during next 1-2 years: í building modiæcations, control room, electrical í EPICS-based vacuum control system í LIGO-I PSL í æxed-spacer è1mè mode cleaner í 4" optics for IR running í scaled èfor 4" opticsè suspensions í full CDS control system: ISC, LSC, ASC, GDS æ And then beyond, to LIGO-II: í Output chamber for signal mirror èchamber exists, seismic stack to be builtè í 7th suspended optic èsmè í control scheme for all optics í strawman: frontal mod with M-Z IFO æ Ready to prototype an RSE scheme by A. Weinstein 40m upgrade LSC, LLO, 3è17è00 4

5 40m upgrade æ Big outstanding questions: í Bake out entire vacuum envelope? í replace viton with damped metal springs in the passive seismic stacks? í replace existing seismic stacks with LIGO-II prototypes? æ Work closely with RSE and multiple pendula development at Glasgow and elsewhere æ The 40m laboratory will continue to be used for testing and staging of other LIGO detector innovations; physicist training; and education and outreach. æ More information: upgrade.html A. Weinstein 40m upgrade LSC, LLO, 3è17è00 5

6 Resonant Sideband Extraction èrseè Config L 1 MC RF RM l 1 BS L 2 PSL l 2 l 3 SM SPD APD PPD A power-recycled Michelson IFO with Fabry-Perot arms, with a signal recycling mirror èsmè for resonant sideband extraction èrseè. A. Weinstein 40m upgrade LSC, LLO, 3è17è00 6

7 Resonant Sideband Extraction æ Signal mirror in dark port decouples carrier storage time ç c in arm cavity èmaximize stored power P ç ç c, h DC ç 1= p P è from signal storage time ç s in arm cavity ètune F-P pole f s = 1=ç s to optimize hèfèè æ For æxed losses, P = P laser GèARMèGèPRCè; RèIT M è controls the ratio GèARM è=gèp RCè æ Maximize ARM carrier gain GèARMè, minimize PRC carrier gain GèPRCè, to minimize beam-heating eæects in BS, ITMs. In absence of RSE, this leads to small f s = 1=ç s æ RSE in broadband conæguration permits low GèPRCè characteristic of a narrow-band IFO, while retaining the shot-noise performance of a broader-band LIGO IFO. æ Optimal sensitivity in the presence of thermal noise will likely require a tuned RSE conæguration, with a dip ëhugging" the thermal noise curve A. Weinstein 40m upgrade LSC, LLO, 3è17è00 7

8 RSE Transmission and shot noise Coupled-cavity transmission: 1 ITM+SEM reflectivity vs phisec ITM+SEM reflectivity RSE SR phisec, radians Shot noise curves for diæerent tunings: RSE shot noise sensitivity detune=0 (top) to pi/2 (bot) RSE Displacement sensitivity (m/rthz) SR Frequency (Hz) red: no SM; high GèARMè, low GèPRCè A. Weinstein 40m upgrade LSC, LLO, 3è17è00 8

9 Fundamental noise at 40m 40m shot noise sensitivity Seismic (viton) Internal Thermal Q = 2.e6 (F Si) strain sensitivity (1/rtHz) ThermoElastic (F Si) No RSE, high band No RSE, low band RSE, broadband RSE, tuned T T T G G f ITM PRM SRM prc arm pol Frequency (Hz) æ Q èf-siè = 2 æ 10 6 æ Thermoelastic, photothermal noise are negligible æ Tuned conæg: ç cs = 0:1 èç cs = 0:63 radiansè æ Laser power turned down, to 400 mw æ Alternatively, live with thermal noise; don't bother to expose shot noise; focus on controls problem A. Weinstein 40m upgrade LSC, LLO, 3è17è00 9

10 Optical Parameters mirror Loss T = t 2 R curv! beam èppmè èmè ècmè ETMs ppm ITMs ppm BS RM SM Arm cavity ænesse = 3919 Arm cavity Gain = 2409 PRC Gain = 7.4 SRC tune ç cs = 0.63 rad h shot èdcè = 4:4 æ 10,21 = p P l h shot è2185hzè = 1:3 æ 10,21 = p P l A. Weinstein 40m upgrade LSC, LLO, 3è17è00 10

11 Controlling the cavity lengths æ The carrier ècè and RF sideband èrf1è light is used to control the 4 relevant length DOFs for LIGO-I conæg: L +, l +, l,, L, æ The addition of one more cavity èsrcè requires additional sidebandèsè æ Simple scheme èjim Masonè: single sideband èrf2è at 3f RF 1 carrier (absent at dark port) f s f c - f 1 fc f c + f 1 f c + f2 f detuned resonance æ applied via frontal modulation with input M-Z IFO mirror/pzt beam recombiner to IFO AOM for SB1 f-shifter for SB2 from PSL beam splitter steering mirror A. Weinstein 40m upgrade LSC, LLO, 3è17è00 11

12 Controlling the cavity lengths æ L + èarms commonè C=RF1 In-phase, PRC PKO æ l + èprc commonè C=RF1 In-phase, SPD æ l, èprc diæè C=RF1 Qu-phase, SPD æ L, èarm diæ, GWè C=RF2 Qu-phase, APD æ l s èsrc lengthè RF 1=RF 2 In-phase, PRC PKO Resonance conditions: æ Carrier resonant in ARMs, PRC æ Carrier resonant èbroadbandedè or de-tuned in SRC æ RF1 resonant in PRC æ RF2 resonant in PRC, SRC Cavity arms PRC SRC carrier R + R + ç s SB1 A R, A SB2 A R, R, TWIDDLE and E2E models in progress! A. Weinstein 40m upgrade LSC, LLO, 3è17è00 12

13 Tunes, frequencies, cavity lengths æ SRC carrier tune: ç cs ç modè2f c l s =cè = 0:1 èchosen to hug thermal noise curveè èin LIGO, chosen to optimize inspiral sensitivityè æ PRC cavity length: l + ç 229:0 cm èæxed by 40m vac envelopeè æ SB1 frequency: f 1 = 32:729 MHz è= c=è4l + èè æ SB2 frequency: f 2 = 3f 1 = 98:188 MHz æ SRC cavity length: l s = 366:4 cm è=, 5, 2ç æ 3 3 cs l+ è æ Schnupp asymmetry and all cavity lengths remain to be optimized! Cavity arms PRC SRC carrier ç ca = 0:00 ç cp = 0:00 ç cs = 0:10 SB1 ç 1a = 8:35 ç 1p = 0:50 ç 1s = 0:80 SB2 ç 2a = 25:05 ç 2p = 1:50 ç 2s = 2:40 A. Weinstein 40m upgrade LSC, LLO, 3è17è00 13

14 Will it fit? 150 cm Signal mirror Output chamber Recycling mirror Beam splitter 25 cm For broadband operation èç cs = 0, worst caseè, need ç 178 cm. Have only ç 150 cm! May only be able to operate with ç cs é ç 0:5 rad! More careful optimizations and drawings are in the works. A. Weinstein 40m upgrade LSC, LLO, 3è17è00 14

15 Additional work accomplished è in progress æ Detailed shot noise modelling æ variations on optical design æ Detailed seismic noise modelling æ Detailed thermal noise modelling æ cavity length optimization æ mirror radii of curvature, spot sizes æ æxed-spacer mode cleaner design æ Twiddle and E2E models æ FFT modeling èso far, perfect optics onlyè A. Weinstein 40m upgrade LSC, LLO, 3è17è00 15

16 Seismic noise Here is the expected contribution to the horizontal displacement, x rms èfè, from seismic motion Horizontal Displacement of a 40m Test Mass (very approximate) metal springs viton springs envelope x(f) in m/sqrt(hz) Frequency (hz) Damped metal springs move seismic wall è100!40è Hz; but larger xè10hzè, x rms, v rms è control problem? x green ç 1 æ 10,8 meters 1 + èf=10è 12:5 h strain = 2 L arm x rms èfè A. Weinstein 40m upgrade LSC, LLO, 3è17è00 16

17 Vacuum Contamination æ 40m has endured anomalous optical losses ègreenè èexpected é 50 ppm; saw ç 200 ppmè æ Is this due to the unbaked vacuum envelope? æ Do the viton springs outgas æourocarbons which degrade high-r optics? æ Are these problems reduced in moving to IR? æ Are they exacerbated in the high-f cavities of the upgrade? æ Overall 40m vacuum is good èç few æ10,6 torrè; hydro- and æourocarbons at ç few æ10,11 ; expect improvements with upgraded system èip'sè æ Contamination test cavity ècamp et alè sees no evidence of degradation with IR æ Bake-out, stack rebuild is a BIG job! A. Weinstein 40m upgrade LSC, LLO, 3è17è00 17

18 People æ Currently: Two physicists èweinstein, Ugoliniè, one master tech èvassè æ Lots of summer REU's æ Hope to make heavy use of LIGO engineers: CDS, optical, mechanical æ Hope to involve more postdocs, grad students, undergrads All LSC personnel are invited and encouraged to contribute and participate as much as possible! A. Weinstein 40m upgrade LSC, LLO, 3è17è00 18

19 æ 3q2000 Schedule, Milestones í lab building repairs and mods í LIGO IR PSL í Construction of new Output chamber, stack í Bakeout? Rebuild existing stacks? æ 4q2000 í Review of optical design consistent with RSEèDR í Development of control system æ 2q2001 í LIGO-like suspensions, controllers, optics in place í LIGO-like CDS: ISC, LSC, ASC, WFS systems í LIGO-like diagnostics, DAQS software í Review of SM control scheme èbroad-band and detunedè æ 2002 í Prototype installation complete. í Initial shakedown complete. í Ready to prototype an RSE scheme. A. Weinstein 40m upgrade LSC, LLO, 3è17è00 19

20 Problems and questions æ Do we need to bake out the vacuum envelope? æ Should we rebuild the seismic stacks, replacing stiæ-but-well-damped viton ècontaminating the vacuum at a low level?è with soft but-poorly-damped metal springs? æ Should we consider employing advanced èscaled downè SEI systems? æ should we consider prototyping advanced SUS systems èmultiple pendula, electrostatic controlè? æ Is the ësimple" control scheme developed by Mason adequate for LIGO-II? æ How can we implement it? M-Z? f RF 2 = 100 MHz? æ Modulation in vacuum or air? Beforeèafter MC? æ where will we get the physicists and eng. support? A. Weinstein 40m upgrade LSC, LLO, 3è17è00 20