INDIAN PARTICIPATION IN GRAVITATIONAL WAVE

DETECTORS AND TELESCOPES : An Assessment of opportunity and readiness

C. S. UnnikrishnanDHEP/Gravitation Group

TIFR, Mumbai

Fundamental Interactions Lab: www.tifr.res.in/~filab

SOME HISTORY:

1960 – TODAY: Initiatives by the Tata Institute of Fundamental Research on ‘LARGE-SCALE’ experimental research (Astronomy & Particle Physics)(Cosmic Muons and Neutrinos, proton decay, EAS, Gamma Ray telescopes…)

1960 – TODAY: Large Scale Radio Astronomy from TIFR and Raman Institute

1981- 1992: Gravitation Experiments on the medium scale - entirely home-built(Equivalence Principle, Long Range forces…)

1997-2004: Small scale, high precision gravity experiments (torsion balances for short-range gravity, Casimir force etc.)

1960 – TODAY: Large scale technology development and implementation by BARC, RRCAT, IGCAR, ISRO etc.

Attempt to start a program on GW detector research (initiated by SVD and others, with a meeting in CAT, Indore) did not take off (1990).(A. Brillet, B.F.Schutz, R. Cowsik, S. N. Tandon, SV Dhurandar….Unnikrishnan, N, Krishnan…)

Why think of starting a serious GW experimental program now?

1) Great technical maturity in the field with clarity on what is needed, and what will succeed in terms of goals set by S/N considerations.

2) Gravitational wave astronomy in sight (<10 years)

3) Lot more funding available in India for large serious projects in fundamental science.

4) Necessity of network of detectors for reliable detection, measurement and astronomy.

5) Confidence that modeling, simulations and data analysis strategies and implementation expertise are available or can be developed in short time.

6) A realistic possibility of a collaboration with AIGO

7) Now or ~Never

8) A reasonable, fair and sure way of participation in LISA

Then WHY NOT go ahead and start?

Lack of instrument builders interested in using such detectors

How many gravitation experimenters are in India?

1+1/2+1/3…

How many Indian experimenters are working in gravity-experiments or in relevant nearby areas?

< 3x (1+1/2+1/3…)

How many are needed to start a project and complete a good prototype in 3 yrs?

3 permanent (100%) + 4 – 6 people contributing 20% time

How many are needed to realize a large size detector, in an international collaboration ? About 5 full time (physics and engg.) + 2 theory + their students ( 10+) + 5 technical

How many are needed for an INDIGO size (Adv. LIGO) project in India (8 – 10 years) ?

10 permanent (physics and engineering) + 20 students/pdf + 20 technical + 5 theory/sim.

Comparison with other large experimental efforts in India

1. Particle Physics Experiments

KGF underground experiments: 2 physics, 5 engineers + 5 technical assistants + 1 or 2 research students at a time+Japanese collaboration (1-2 physics people + 1 student at a time)

Proton decay detector and experiment at a scale much larger than a prototype GW detector, though relatively simpler technically than a full GW detector

This is a good example to assess whether it is reasonable to think that we can do ‘it’.

Note: It is the research student of 1980s leading the $150 million INO neutrino project today, and a prototype is nearly ready in 3 years.

INO today: 2 – 3 physics experimentalists, 4 - 6 engineers + technical staff, and ~20 theorists. Realistic plan to expand quickly after full funding approval and clearances.

2. Radio Astronomy at TIFR

1960s: 3 - 4 radio astronomers + professional private engineering help -> Ooty radio telescope, 0.5 km steerable parabolic dish (5 years)

1990s: 1 super-pusher+ 5 radio astronomers + 10 engineers + technical staff + industry help

Pune telescope: 45 meter dia. steerable dishes and the electronics x 25(Cost reduction by factor 3 or more by careful and simple design)

This effort was comparable in terms of thought and execution to a large GW detector, given that the technology used in other GW detectors is openly available and does not require development from scratch.

Crucial factor: The builders were also the first or prospective users

3. TIFR Gravitation LaboratoryGauribidanur, Karnataka

2 faculty members 2 students 4 years4 engineer/technical

Experiment

2 3 4 5 6 7 8 9 10

4.2

4.4

4.6

4.8

5.0

5.2

Lo

ck V

olta

ge

(V)

Separation(microns)

Sensitivity: 10-12 Newton

G. Rajalakshmi et al, Marcel Grossman meeting 2006

Though small scale, they were able to reach close to design goals, and with continued efforts could have become among the best operating torsion balances

GG Space experiment

1 Faculty member + 2 retired faculty + 1 student + 2 post-docs + industry help (fund-dependent)

GG (Galileo Galilei) Space-based experiment

GROUND TESTS: GG ON GROUND – GGG

GGG lab 2005 (March) GGG lab 2005 (March) GGG in INFN lab, Pisa GGG in INFN lab, Pisa

1m

Suresh Doravari is a key member

Lasers and Optics

(From BEC experiments)

Raja Rao, A.S.*; Singh, R* Design and engineering of the large vacuum system of the gravitational wave detector-AIGO IVS Bulletin v.27, no.1 (1996)

N. Krishnan, Vibration Isolation Systems for Gravitation Experiments (unpublished study)

Capabilities at a glance (partly guess):

1) Vacuum design and implementation: 50 - 100 meter prototype OK 3 km detector Perhaps

(standard imported pumps and valves , Indian pipes, welding and seals, NEG pump technology, develop compact version of RRCAT ion pumps… etc.

2) Vibration Isolation : OK (CLIO + AIGO features)

3) Lasers : Help from Europe essential(Explore fiber lasers)

4) Optics : Need help for high finesse low loss optics

5) Interferometer (FP-Michelson with mode cleaner, and power cycling : Prototype OK. Beyond, need

help.

6) Electronics (lock etc) : Prototype OK 3 km detector OK

7) Data handling : Obviously OK

93 10 mbar

1810 / @100Hz Hz

What is feasible realistically within 3 - 4 years in India?

A good prototype of 50 -100 m length.

What is feasible realistically within 3 - 4 years in India?

A good prototype of 50 -100 m length.

If we do, what is a roadmap?

1) Policy decision by at least 3 major research institutes that this is thrust area in their research plan, with approval for 4 - 5 recruitment in experimental areas and 2 in theory within the next 2-3 years (It is already a thrust area in the DST plan documents)

2) Formation of consortium of people already interested, and start on the project with a 50+ meter prototype as a focal point ($ 4 million/ 20 crores). 2 full time members at this stage required as new recruits.

3) Complete operating prototype within 3 years (strain sensitivity better than @ 100 Hz) with the help of collaborations1810 / Hz

All these in the context of AIGO or INDIGO ?!

How many gravitation experimenters are in India?

1+1/2+1/3…

How many Indian experimenters are working in gravity-experiments or nearby areas?

< 3x (1+1/2+1/3…)

How many are needed to start a project and complete a prototype in 3 yrs?

3 permanent (100%) + 4 – 6 people contributing 20% time

How many are needed to work in collaboration with a large size detector?About 5 full time (physics and engg.) + 2 theory + their students ( 10+) + 5 technical

How many are needed for an INDIGO size project

10 permanent (physics and engineering) + 20 students + 20 technical + 5 theory/sim.

If INDIGO, there could be a realistic strategy:

For a 4 km interferometer, costing $130 M (650 Crores), the cost of ‘vacuum’ dominates – almost $100 M.

Vacuum system is scalable, and end points of the interferometer can be shifted as upgrades.

So, one could build a $50 M scalable interferometer, < 1 km long, and still have a sensitivity better than present LIGO and start operation in half the time, exploiting all the new technologies and also some borrowed equipment. If LIGO hardware is going to be used, this is the best strategy in my view. Even for AIGO, this 2-step strategy could be considered if funds become an issue.

INDIAN PARTICIPATION IN GRAVITATIONAL WAVE DETECTORS AND TELESCOPES : An Assessment of opportunity and readiness

Opportunity and encouragements: PlentyFunds : Possible availability for feasibility study and prototypeEnthusiasm among people who cannot build: OverwhelmingInterest among people who can build parts: Miniscule

People who are capable, willing and technically competent to handle (PI) an advanced time-bound GW project in India: 0

People who are capable and technically competent to participate in an advanced GW project in collaboration: Perhaps 2 or 3, and still need convincing

Is there any Indian experimentalist somewhere, who will take a lead by his own interest and drive in a large GW detector project in the next 3 years? NO

Anything to change this situation is what is needed. That is where a national research policy involving top institutes and some assurances becomes important.

Q: Why are you not taking the responsibility?

I think that some of our foundational theories need a drastic revision, and at present I am working on them with some supporting experiments. For example, on the postulated but untested hypothesis of the invariant relative speed of light. Another is the empirically well-supported theory of Cosmic Relativity.

This leaves me not enough time for working on GW astronomy, though I can manage to work for realizing a prototype, if there is a larger context.