Shui-Ming Hu University of Science & Technology of China (USTC) Hefei, China June 17, 2014, ISMS-UIUC Doppler broadening thermometry based on cavity ring-down spectroscopy TJ12 Beijing Shanghai Hongkong Where is Hefei? DD 00 Parameter cm 00 DD TkBkB Uncertainty0~ 10 ppb< 1 ppb?1ppm Doppler Broadening Thermometry (DBT) C. Daussy, et al., Phys. Rev. Lett. 98, (2007); C. Lemarchand et al., New J. Phys. 13, (2011). G. Casa, et al., Phys. Rev. Lett. 100, (2008); L. Moretti et al., Phys. Rev. Lett. 111, (2013) Determination of Boltzmann Constant k B (CODATA2010) AGT: acoustic gas thermometry RIGT: refractive index gas thermometry JNT: Johnson noise thermometry INRIM: Istituto Nazionale di Ricerca Metrologica, Torino, Italy LNE: Laboratoire national de metrologie et dessais,Trappes, France NIST: National Institute of Standards and Technology, USA NPL: National Physical Laboratory, Teddington, UK AGT k B = (13) E-23 J/K Rel. Uncertainty 1ppm Uncertainty budget in DBT Moretti et al, PRL 111: (2013) SNR of spectrum, 300 ppm (single scan) Pressure induced broadening effects, Pa Laser line width, 1MHz Better sensitivity? Better precision? Cavity ring-down spectroscopy (CRDS) Very high sensitivity L eff ~ 10,000 km Large dynamic range I =I 0 exp(-t/) Timet=0 Intensity 00 Frequency drift C 2 H 2 ro-vibrational line at 12629cm -1 C 2 H 2 60 Pa Laser-Locked CRDS Ring-down Cavity Laser Peak Lock ULE-FPI Etalon Lock etalon /2 PZT DAQ PD v0v0 Switch EOM v 0 -f m v 0 +f m v0v0 Microwave Pan et al, Rev. Sci. Instrum. 82:103110, 2011 Laser frequency Precision: ~10 kHz Dynamic range: ~10 GHz Absorption coefficient Sensitivity: ~ /cm Dynamic range: >10 5 Sensitivity & Precision of LL-CRDS Freq. combs Freq. Ref. Microwave scan Gao et al, Rev. Sci. Instrum. 81:043105, 2010; Cheng et al, Opt Express, 20:9956, 2012 Pan et al, Rev. Sci. Instrum. 82:103110, 2011 Sun et al, Opt Express 19: (2011) Higher sensitivity Measurement with low sample pressures Better precision Scan with microwave Superior linear dynamic range Temperature-Stabilized Ring-down Cavity T 1 - T 2 = 0.32(1) mK AOM 1 AOM 2 MBR110 PBS Pol /4 Det2 Det1 Det3 BS ULE-FPI Det4 PZT Hart 5686 Heating wire EOM v0v0 v 0 -f m v 0 +f m v0v0 T controlled etalon PBS Etalon lock PZT v 0 +f m RF synthesizer GPS-disciplined Rb clock EOM C 2 H 2 ~3.3Pa 100 s each scan SNR~10,000 Statistical uncertainty in determined line width N: number of scans DBT Temperature from different line-profile models USTC Dr. Cun-Feng Cheng Dr. Yu Sun Dr. An-Wen Liu Jin Wang, Yan Tan NIM Dr. JinTao Zhang Thank You for Attention! Summary CRDS allows DBT measurement at lower pressures in near-IR; Laser-locked CRDS allows spectral scan with high precision; RD cell thermo-stabilized to Statistical uncertainty