The CCL-K11 ongoing key comparison Final report for period

Transcription

1 The CCL-K11 ongong key comparson Fnal report for perod Mchael Matus BEV, Arltgasse 35, 1160 Wen, Austra Kaj Nyholm MIKES, P.O. Box 9, 0151 Espoo, Fnland Alan A. Madej, John E. Bernard INMS/NRC, 100 Montreal Rd., ON K1A 0R6, Ottawa, Canada Jerzy Walczuk GUM, Elektoralna St., Warszawa, Poland Lucja Črepnšek Lpuš MIRS, Smetanova 17, 000 Marbor, Slovena Héctor A. Castllo M., Rene Pchardo Vega CENAM, Km 4,5 Carretera a Los Cués, CP 7641 Queretaro, Méxco Karna Beatrz Bastda, María Grselda Mngolla INTI, Colectora de Avenda General Paz 5445, B1650KNA San Martín, Buenos Ares, Argentna Igor Malnovsk, Luz Tarelho, Rcardo França INMETRO, Av. N. Sra. das Graças, 50 Xerèm, Duque de Caxas, Ro de Janero, Brazl Ramz Hamd, Ersoy Şahn UME, Tübtak GebzeYerleşkes, PO 54, 41470, Turkey Marko Katć, Vedran Šmunovć DCM/LFSB, Ivana Lucca 1, Zagreb, Croata Lennart Robertsson BIPM, Pavllon de Breteul, 931 Sèvres, France

2 Fnal report on CCL-K11 for perod Abstract Lasers from nne natonal metrologcal nsttutes (NMIs) were compared as part of the CCL- K11 ongong key comparson, ntated by the 13 th meetng of the Comté Consultatve des Longeurs (CCL) n 007. The absolute frequency of the f component of the R(17) 11-5 transton of molecular odne was measured for these lasers followng the techncal protocol for CCL-K11. The results of these measurements are compled n the present report. The comparson reports, as communcated by each partcpant, are ncluded as appendces. Introducton The BIPM.L-K10 (K10) key comparson was ntated n 1993 to provde a bass for demonstratng equvalence of natonal realzatons of wavelength-standards used for the realzaton of the defnton of the metre accordng to the method (c) n what was called the Mse en Pratque (MeP, refers to the document Practcal realzaton of the defnton of the metre ). Such a comparson seemed of partcular mportance snce the whole feld of dmensonal metrology had to be traceable to such realzatons of the metre. The K10 comparson took only the 633 nm He-Ne standards nto consderaton. The measurand of the comparson was the dfference of the average frequency of the hyperfne components d, e, f, and g n the R(17) 11-5 lne as obtaned by matrx measurements. The frequency of the reference laser BIPM4 was used as the key comparson reference value, representng the value recommended n the MeP. The stuaton for realzaton of the SI-metre has changed due to the ntroducton of new technques for absolute frequency measurements. Ths has opened up the alternatve method (b) n the MeP to realze a frequency/wavelength standard traceable to the SI-second. The practcal consequences of ths development are that at least two methods are at the moment beng used to realze the metre, and that standards of dfferent wavelengths, mportant for dmensonal metrology applcatons, can now demonstrate traceablty wth relatve ease. Consderng these crcumstances the 11 th CCL meetng whch was held n October 003 at the BIPM decded to close the K10 comparson and ntate a new key comparson named BIPM.L-K11. Frst measurements n BIPM.L-K11 were made at the BIPM n May 004. Results from BIPM.L-K10 and BIPM.L-K11 can be found at Subsequently, the CIPM has decded, that the comb-related work, whch used to provde external servces, should stop at the BIPM at the end of 006. Ths decson had drect mplcatons on the actvty whch supported the BIPM.L-K11 that consequently were closed down at the end of year 006. A proposal for a new scheme for the comparson, based on a group of node-laboratores n the dfferent RMOs and ploted by the Bundesamt für Ech- und Vermessungswesen (BEV, Austra) was therefore made. Ths proposal, whch had been agreed on by the Presdent of the CCL, was gven support by the CIPM at ts 95 th meetng and was endorsed by the 13 th meetng of CCL n September 007. The techncal protocol (avalable from the BIPM web page) defnes the procedures to follow n ths new comparson, now transferred to the CCL, and named CCL-K11. CCL-K11 page

3 Fnal report on CCL-K11 for perod Measurements and Evaluaton The measurements for the reported campagn took place at the node laboratores MIKES, the BEV, and the NRC, respectvely. All partcpants took part wth odne stablzed HeNe-lasers at λ 633 nm workng on the f or component of the 17 I R(17) 11-5 transton. Table 1 lsts the measurements n chronologcal order, specfyng the partcpants, the places and the dates. Table 1. Partcpants Country NMI Standard Contact person Node lab Date Fnland MIKES MRI3 K. Nyholm MIKES Dec. 007 Poland GUM GUM1 J. Walczuk MIKES Dec. 007 Slovena MIRS MIRS1 L. Črepnšek Lpuš BEV Mar. 009 Austra BEV BEV1 M. Matus BEV Mar. 009 Mexco CENAM CENAM1 H.A. Castllo M. NRC Sep. 009 Brazl INMETRO INMETRO PR-00 I. Malnovsk NRC Sep. 009 Argentna INTI INTI1 K.B. Bastda NRC Sep. 009 Turkey UME UME-L3 R. Hamd BEV Nov. 009 Croata DCM/LFSB LFSB-1 V. Mudronja BEV Dec. 009 All measurements reported here were performed accordng to the so-called method m1 (Absolute frequency measurement traceable to the realsaton of the SI second), whch are measurements usng femtosecond frequency combs. The femtosecond comb arrangements n the node laboratores are outlned n the appendces of ths report. Intally to the actual measurements each partcpatng laboratory had to state: The expected frequency of the standard, f e. Ths should normally be the frequency used n ther calbraton servce. It s ether the recommended value or a value determned by some other means. The standard uncertanty u e of the expected value. Ths should be a value compatble wth the uncertanty gven n the CMC for ths servce. The operatonal parameters used to obtan the two values mentoned above. Senstvty coeffcents wth uncertantes for parameters appearng n the uncertanty budget for the standard. The stated frequency f e s the actual measurand n ths type of key comparson. It s compared on a per lab bass, wth the measured frequency f m corrected to the reference operatonal CCL-K11 page 3

4 Fnal report on CCL-K11 for perod parameters as gven below. One has to note, that the comparson s carred out as a blnd measurement, where the partcpant does not know f 0 nor f m before statng f e. The standard uncertanty of the determned frequency s composed of two parts, one from the frequency measurement, u 0, and one from the uncertanty n the settngs of the workng (and other) parameters, u p. The latter, the uncertantes related to the standard tself are to be estmated by each operator n accordance wth ther qualty system. The uncertanty stemmng from the measurements, u 0, s estmated by the operator of the experment alone, or together wth personnel nvolved n the comparson, agan n accordance wth a qualty procedure. These uncertantes are reported n sectons D8 and D9 and should be gven as standard uncertantes followng GUM practce. The combned uncertanty of u 0 and u p, u m, reported n D10 should be gven as the root sum squares of u 0 and u p. Denote, the measured (uncorrected) frequency f 0 wth standard uncertanty u 0, and the measured frequency, corrected for nfluence of operatonal parameters f m wth standard uncertanty u m. Then the followng holds: f f δ (1) m = 0 The symbol δ denotes the condensed nformaton about the nfluence of the actual workng parameters and other quanttes on the laser frequency. A lnear model s commonly used for ths: s x + δ = δ () Where the s denote the senstvty coeffcents and x the devatons of the respectve workng parameters from the nomnal values (care must be taken choosng the correct sgns for both quanttes). All other nfluence quanttes (e.g. electronc offsets, cavty algnments, etc.) are modelled wth the δ. These have usually zero expectaton values but non-zero uncertantes. The uncertantes are thus derved n a straghtforward way as: and ( ( ) u s x ) + ( s u( x )) u( ) + up = δ (3) m p 0 CCL-K11 page 4 u = u + u (4) Denote, the expected frequency f e wth standard uncertanty u e, and the measured frequency, corrected for nfluence of operatonal parameters f m wth standard uncertanty u m. For a partcular standard,, construct the dmensonless quanttes ( ) ( ) fm( ) f ( ) fe f = (5) u r r ( ) m ( ) + um( ) f ( ) ue = (6) m It must be noted that f e and f m should be transferred to the same (usually nomnal) workng parameters for the standard, whch would be expected to concde wth those for whch f e s vald f no other nstructons are gven by the partcpatng laboratory.

5 Fnal report on CCL-K11 for perod CCL-K11 s not ndented to derve a better value for any of the frequences from the lst of recommended radatons for the realsaton of the metre and other optcal frequency standards (formally known as MeP). Therefore t s not mandatory that f e s a value out of ths lst, nor s t necessary to correct for the nomnal workng parameters. It s however necessary for each partcpant to follow hs nternal workng procedures lke for any calbraton for the respectve CMC entry. To test consstency between the measured values and the expected ones, hypothess testng at a confdence level of 95 % s to be performed. The result wll serve as a bass for the revew of the CMC and ndcate the compatblty wth the clamed capabltes. In ths framework the degree of equvalence can be obtaned n the usual way. The consstency can thus be checked by the followng condton: 1 fr ( ) E n = 1 wth U r ( ) ur ( ) U ( ) r = (7) As dscussed at the 14 th CCL meetng, June 009, t s not necessary nor useful to determne a par-wse degree of equvalence. For all results reported the expanded uncertanty to a 95 % confdence level can be obtaned by multplyng the standard uncertantes wth k =. Table gves the values used for the most mportant workng parameters for each laser. Addtonal nformaton can be found n the appendces. Table. Workng parameter values for the standards wth estmated standard uncertantes n parenthess as gven n the measurement reports ncluded n the appendces. Note that some of them devate from the CIPM recommended values. Standard f n µw Modulaton wdth (peak to peak) n MHz I cold-fnger temperature n C Cell wall temperature n C MRI3 44 (4) 6.0 (0.1) 15.0 (0.1) 5.0 (1.4) GUM (1.) 6. (0.1) (0.06) 4.0 (1.4) MIRS1 66 () 6.0 (0.) 15.0 (0.1) 30.0 (.0) BEV1 115 () 6.0 (0.) (0.10) 5 (5) CENAM1 85 (10) 6.0 (0.3) 15.0 (0.) 5 (5) INMETRO PR (10) 5.98 (0.10) 14.9 (0.) 7 (1) INTI (10.0) 6.0 (0.3) 15.0 (0.) 5 (5) UME-L3 90. (3.0) M (3.0) M 6.0 (0.1) (0.003).7 (1.0) LFSB-1 80 (3) 6.0 (0.3) 15.0 (0.) 4 (1) Results The stated frequences f e and the measured frequences f 0 and f m are gven n table 3. The allocated standard uncertantes u e, u 0 and u m, respectvely, are ncluded n parenthess. Nearly half of the partcpants estmate f e and u e by usng the CIPM recommended values for the f CCL-K11 page 5

6 Fnal report on CCL-K11 for perod component of the R(17) 11-5 transton. The remanng partcpants use other sources of knowledge to estmate these values (ether comb calbratons n ther home laboratores or results from former comparsons). INMETRO even chooses the component of the R(17) 11-5 transton. Two partcpants (MIKES and GUM) choose not to correct the measured frequences wth the nfluence of the actual parameter values. Of course the uncertanty stemmng from assumed devatons s part of budget. At the NRC many ndvdual frequency measurements wth sometmes dfferent parameter settngs were performed for the three respectve standards. Each raw frequency value was ndvdually corrected and a weghted mean value for f m s reported. It s therefore not sensble to state a sngle f 0 value n table 3. Detals can be found n the appendces. The data from table 3 are used to calculate the fnal results accordng to equatons (5-7). The results are gven n table 4 and fgure 1, respectvely. Table 3. Expected frequences f e, measured (uncorrected) frequences f 0, and measured frequences, corrected for nfluence of operatonal parameters f m together wth the respectve standard uncertantes of the standards. Standard All frequences gven are offset by MHz (n the case of INMETRO by MHz) f e (u e ) / khz F 0 (u 0 ) / khz f m (u m ) / khz MRI (10.0) (.8) (.8) GUM (1.0) 60.1 (5.5) 60.1 (5.5) MIRS (1.0) (.0) (4.4) BEV (1.0) 61.1 (.0) (3.) CENAM (1.0) *) (0.4) INMETRO PR (10.0) *) (0.3) INTI (10.0) *) (0.9) UME-L (3.) 59.4 (.0) 59.1 (.9) LFSB (1.0) (.) (.8) *) Indvdual frequency measurements wth dfferent parameter settngs performed. It s not sensble to state a sngle value for f 0. CCL-K11 page 6

7 Fnal report on CCL-K11 for perod Table 4. Degree of equvalence for the standards. Standard f r u r E n = f r U r MRI GUM MIRS BEV CENAM INMETRO PR INTI UME-L LFSB Fgure 1. Degree of equvalence for the standards. Error bars represent the expanded uncertantes U r () CCL-K11 page 7

8 Fnal report on CCL-K11 for perod Concluson Frequency measurements have been carred out on 9 natonal wavelength standards. A good agreement between the stated and the measured frequency values was found. No correctve actons are necessary for any of the partcpants. Appendces Detals on the ndvdual standards can be found n the measurement reports collated n the appendces. These reports are electronc copes, the sgned orgnals are kept by the node laboratores. The techncal protocol was revsed a few tmes durng the perod reported therefore there s some lack of unformty n the layout of the reports. Mchael Matus, BEV (AT) Plot of CCL-K May 010 CCL-K11 page 8