1 Status Report on Time and Frequency Activities at NPL India A. Sen Gupta, A. Chatterjee, A. K. Suri, A. Agarwal, S. Panja, P. Arora, S. Yadav, P. Kandpal, M. P. Olaniya (APMP -TCTF 2012) (Wellington – Nov 2012)

Major activities Time and Frequency Metrology –Generation of UTC(NPLI) –BIPM Link using GNSS –BIPM Link using TWSTFT Cs Fountain Frequency Standard –Evaluation of the first Cs Fountain – in progress. –Design and development of the second Cs Fountain. Time Dissemination –Dissemination by Telephone Time broadcast (Teleclock), and NTP server. Calibrations –Atomic Clocks (Rb & Cs Freq Standards), Time Interval Counter, Hour Meter, Teleclocks, GPS timing receivers and Stopwatch. –Providing traceability to IRNSS time scale. Optical Frequency Standards –Plans and initial activity on single trapped Yb + ion standard.

Schematics of Generation of UTC(NPLI)- 1 5 MHz 1PPS UTC(NPLI)

Schematics of Generation of UTC(NPLI)- 2 Cs Clock A-C001 Cs Clock A-C001 Cs Clock A-C001 Cs Clock A-C001 Cs Clock A-C001 Cs Clock A-C001 Cs Clock 75071A-C A-C001 Cs Clock 85071A-C A-C001 Micro Phase Stepper Ф resolution= 2π(2 -32 )rad. Freq. Resolution = 5E-19 Micro Phase Stepper Ф resolution= 2π(2 -32 )rad. Freq. Resolution = 5E-19 Multi-Channel DMTD Phase Comparator 5 MHz 1 PPS 5MHz 1PPS 5 MHz Controller Workstation 1PPS 5MHz IN out IN out 5 MHz out FREQUENCY DOUBLER 5 MHz 10 MHz 1PPS 5 MHz Distribution Amplifier-1 5MHz out Hydrogen Maser - HM1 MHM2010 Hydrogen Maser - HM1 MHM2010 1PPS 5MHz MHz Micro Phase Stepper(Aux) IN out MHz 1PPS To Calibration Lab To Satellite Links To Fountain Lab UTC(NPLI) - Aux UTC(NPLI)

Photograph of the Clock Setup at NPLI

Distribution Amplifier-2 Pik Time TTS2A Sngl Freq GPS Rx Pik Time TTS2A Sngl Freq GPS Rx Pik time TTS4 Dual Freq GPS Rx Pik time TTS4 Dual Freq GPS Rx 10 MHz 1PPS 10 MHz 1PPS 10 MHz 1PPS 10 MHz 1PPS Workstation for controlling SATRE MODEM operation Saw Filter 2.5MHz Antenna Control unit Beacon Receiver Workstation for controlling GPS Rx operation PolaRx3eTR Dual Freq GPS Rx PolaRx3eTR Dual Freq GPS Rx Schematics of GNSS and TWSTFT Links

Photographs of GNSS and TWSTFT Links

Typical GPS P3 Link Results UTC(NPLI)-UTC(PTB), ns MJD UTC(NPLI)-UTC(PTB), ns σ = 1.2 ns

Typical GPS Carrier Phase PPP Results UTC(NPLI)-UTC(PTB), ns MJD Using NRCAN PPP Software developed by Dept of Naural Resources, Canada σ = ns

Typical TWSTFT Results on the Eu-Asia Network UTC(NPLI)-UTC(PTB), ns MJD σ = ns

UTC - UTC(NPLI) from BIPM Circ-T UTCr - UTC(NPLI) – BIPM Pilot Expt

First Cs Fountain (India-CsF1) Front View x 20l/s Ion Pumps Octagonal MOT Chamber Detection Zone Cs Free Flight UHV Chamber 3 Layers of Magnetic shields C-Field Solenoid Microwave Cavities 2 x 55 l/s Ion Pumps India Cs-F1 is fully Operational and is presently being evaluated

(u total ) 2 = (u A ) 2 +(u B ) 2 +(u link/lab ) 2 India-CsF1 – Typical Results EffectBias (x )Uncertainty (x ) 2 nd order Zeeman AC Stark (BBR) Collisions*1.0 (approx) Gravity Other effects*0.1 (approx) Total, u B 1.0 * to be evaluated

Second Cs Fountain (India-CsF2) (1, 1,1) geometry for cooling and launching Two coils in anti-Helmholtz configuration Three pairs of rectangular Helmholtz coils Two detection beams of 10 mm x 10 mm Optical pumping to enhance the m f = 0 population

Time Dissemination Teleclock Service Domain name: time.npli.in Internet Time Service

Calibration Services We are providing Time & Frequency in house Calibration Services to Test & Calibration Labs from Govt. and Industries for the calibration of Rb & Cs Atomic Clocks, Time Interval Counters, Hour meters, Teleclocks, GPS receivers and Stop watches We are providing UTC Traceability to the Time scale of the Indian Regional Navigational Satellite System (IRNSS). This Time scale is known as the IRNWT and is maintained by the Indian Space Research Organization (ISRO). The technique used presently is all in view GPS P3. We are planning to supplement this with a dedicated TWSTFT link.

New Developments We have just received funding to start work on a Single Trapped Ion Optical Frequency Standard. We plan to work on Yb + ions. We plan to move some our activities to the New Metrology Building next year.

Thank You for your Attention