Review - LIGOajw/40m/40m_000516.pdf · Review of 40m upgrade go als The primary goal of the 40 m...

40m Upgrade Plans

� Review of 40m upgrade goals

� 40m infrastructure upgrade

� RSE con�guration - design considerations

� IFO optical con�guration

� RSE control scheme

� people, money, schedule

� problems and questions

http://www.ligo.caltech.edu/�ajw/40m 000516.pdf

A. Weinstein 40m upgrade meeting, 5/16/00 1

Review of 40m upgrade goals

� The primary goal of the 40 m upgrade

is to demonstrate a scheme for using

resonant sideband extraction (RSE),

in either broadband or tuned con�g,

appropriate for an optimal LIGO con�g

� RSE and DR have been demonstrated at

Garching 30m, and at table-top IFOs

� An RSE/DR con�g appropriate for LIGO

will be demonstrated at the Glasgow 10m

� For LIGO, need a full engineering prototype,

using LIGO electronics and control scheme.

This is the primary goal of the 40 m upgrade.

� Complements work at other R&D facilities:

{ 40m will focus on shot (phase, sensing) noise, high-f

{ LASTI: full-scale SEI,SUS prototyping; low-f

{ TNI: thermal noise; middle-f

{ ETF: Sagnac, high powered lasers


Secondary 40m upgrade goals

Prototype \everything"?

� potentially, multiple pendula SUS

| this may be necessary, to extrapolate experience

gained at 40m to LIGO-II

� potentially, advanced SEI systems

| scaled down, of course. Cannot replace full-scale

testing at LASTI.

� potentially, thermal noise measurements

with maximized beam width (� at mirrors)

| a big, and challenging, diversion.

� LIGO-III: cryogenic TMs, QND, etc..

� physicist training

At the least, must prototype everything that has

large impact on electronics/control system,

for a meaningful full engineering test!


40m infrastructure upgrade

� LIGO-like upgrade, during next 1-2 years:

{ building modi�cations, control room, electrical;

work to be completed by fall (???)

{ Active seismic isolators on TM stacks?

{ EPICS-based vacuum control system

(to be completed by summer)

{ LIGO-I PSL from Peter King (fall?)

{ 12 meter mode cleaner and MMT

(vacuum envelope, stack, exists)

{ 4" optics for IR running

{ 7th suspended optic (SM)

{ scaled (for 4" optics) suspensions

{ Output chamber for signal mirror

(chamber exists, seismic stack to be built)

{ full CDS control system: ISC, LSC, ASC, GDS

{ control scheme for all optics

{ strawman: frontal mod with M-Z IFO

� Ready to prototype an RSE scheme by 2002.


Seismic noise

We have measured the seismic noise (V,H; day, night) at

the 40m lab:

100

101

102

10−16

10−14

10−12

10−10

10−8

10−6

10−4

Frequency (Hz)

Dis

plac

emen

t noi

se, m

/ rt

Hz

40m displacement noise

Starting GPS time:Wed Apr 12 02:17:43 2000 (and 0 usec)

Hanford IFO−Seis Floor−X Floor−Y Floor−Z Microphone

100

101

102

10−12

10−11

10−10

10−9

10−8

10−7

10−6

zrmsnite = 0.13 µm

zrmsday = 0.23 µm

nightday

100

101

102

10−10

10−9

10−8

10−7

10−6

10−5

vrmsnite = 1.64 µm/s

vrmsday = 3.13 µm/s

nightday

100

101

102

10−8

10−7

10−6

10−5

10−4

10−3

armsnite = 1929 µm/s2

armsday = 1809.59 µm/s2

nightday


Stack transfer function

V,H transfer functions of the existing TM stacks:

100

101

102

10−4

10−3

10−2

10−1

100

101

102

Frequency (Hz)

Hor

izon

tal T

rans

fer

func

tion

40m displacement noise 12−Apr−2000 03:17:30 PDT −−− Horizontal

Seismic+Geo Shaker+AccelShaker+Geo Model

100

101

102

10−4

10−3

10−2

10−1

100

101

102

Frequency (Hz)

Ver

tical

Tra

nsfe

r fu

nctio

n

40m displacement noise 12−Apr−2000 03:17:30 PDT −−− Vertical

Seismic+Geo Shaker+AccelShaker+Geo Model


Active seismic isolation?

STACIS isolator pedestals (roughly $120K)

For robust IFO lock, need mirror horizontal vrms � �=s

�lock ��=2

vthrP (v < vthr); vthr ' 1�=s

100

101

102

10−16

10−14

10−12

10−10

10−8

10−6

10−4

vrmsfloor = 1.64 µm/s

vrmsmirr = 0.43 µm/s

vrmsSTACIS = 0.27 µm/s

Frequency (Hz)

velo

city

noi

se p

ower

spe

ctru

m, µ

m/s

/ rt

Hz

40m displacement noise 12−Apr−2000 03:17:30 PDT

vrms

, floor v

rms, mirror

vrms

, STACIS


Resonant Sideband Extraction(RSE) Config

South

East Arm

ArmL1

l 3

l 2l 1

PSL

RM

L2

RF 12m MC

APD PPDSPD

BS

SM

A power-recycled Michelson IFO with Fabry-Perot arms,

with a signal recycling mirror (SM) for resonant sideband

extraction (RSE).

� LSC/AIC group is evaluating di�erent control schemes.

� Key parameters depend on what is chosen:

{ TITM , TSM , LSRC , LPRC

{ Method for applying sidebands to beam

� Hope to have a workable scheme by fall

� May have to fold SRC!!


Will it fit?

150

cm

Output chamber

Beam splitter

25 cm

Recycling mirror

Signal mirror

For broadband operation (�cs = 0, worst case),

need � 178 cm. Have only � 150 cm!

May be limited in available tune,

or may have to fold the SRC optical path.

More careful optimizations and drawings are in the works

(Mike Smith).


Fundamental noise at 40m

101

102

103

104

10−22

10−21

10−20

10−19

10−18

10−17

10−16

40m strain sensitivity

stra

in s

ensi

tivity

(1/

rtH

z)

Frequency (Hz)

TITM

TPRM

TSRM

Gprc

Garm

fpol

0.030 0.000 0.176 10 131 9516

Seismic

FSilica Thermal

Suspension

RSE, tuned

Radiation pressure

40m RSE total

� Thermoelastic, photothermal noise are negligible

� Suspension noise may be trouble with 3" optics

� Q (F-Si) = 2� 106. Dominates from 100{3KHz!

� May need to turn laser power down

to expose shot noise over thermal;

� Alternatively, live with thermal noise;

don't bother to expose shot noise;

focus on controls problem


People

� Currently: Two physicists (Weinstein, Ugolini),

one master tech (Vass)

� MUST make heavy use of LIGO engineers:

{ building modi�cations: Fred Asiri

{ Output chamber stack: Fred Asiri

{ active isolators?: Larry Jones

{ PSL-I: Peter King, Rich Abbott

{ optics: Garilynn Billingsley

{ single ! multiple pendula: Janeen Romie

{ optical layout, ba�ing: Mike Smith

{ CDS (ISC, LSC, ASC): Jay Heefner, Rolf Bork,

new hire

� Expect to hire another controls engineer/postdoc

� MUST involve more postdocs, grad students,

undergrads

� MUST involve LSC personnel


Summer REU's

� Lisa Goggin, University College, Cork:

12 meter mode cleaner

� Jitesh Chauhan, Leicester U:

Global Diagnostics System

� Brian Kappus, Harvey Mudd:

Wavefront sensing

� Ted Jou, Caltech:

RSE modelling; Twiddle/Finesse ! E2E

� Ivica Stevanovic, Belgrade U:

multiple pendulum modelling


Schedule, Milestone Fantasy

� 3q2000

{ lab building repairs and mods

{ LIGO IR PSL

{ Construction of new Output chamber, stack

{ Bakeout? Active isolators?

� 4q2000

{ Review of optical design consistent with RSE/DR

{ Development of control system

� 2q2001

{ LIGO-like suspensions, controllers, optics in place

{ LIGO-like CDS: ISC, LSC, ASC, WFS systems

{ LIGO-like diagnostics, DAQS software

{ Review of SM control scheme

(broad-band and detuned)

� 2002

{ Prototype installation complete.

{ Initial shakedown complete.

{ Ready to prototype an RSE scheme.


Problems and questions

� Do we need to bake out the vacuum envelope?

� Should we rebuild the seismic stacks,

replacing sti�-but-well-damped viton

(contaminating the vacuum at a low level?)

with soft but-poorly-damped metal springs?

� Should we consider employing

advanced (scaled down) SEI systems?

� should we consider prototyping advanced SUS systems

(multiple pendula, electrostatic control)?

� Is the \simple" control scheme developed by Mason

adequate for LIGO-II?

� How can we implement it? M-Z? fRF2 = 100 MHz?

� Modulation in vacuum or air? Before/after MC?

� where will we get the physicists and eng. support?


Review - LIGOajw/40m/40m_000516.pdf · Review of 40m upgrade go als The primary goal of the 40 m...

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