DOI:
10.7795/720.20201113

Title: 
Additional data for the publication "Long term measurement of the 87Sr clock frequency at the limit of primary Cs clocks"

Summary: 
The data sets provide additional information on the experiments and the physical background discussed in the publication entitled "Long term measurement of the $^{87}$Sr clock frequency at the limit of primary Cs clocks" in Physical Review Research (DOI: 10.1103/PhysRevResearch.2.033242).

Creators: 
	Roman Schwarz, 4.3, https://orcid.org/0000-0002-5841-5597
	Sören Dörscher, 4.3, https://orcid.org/0000-0002-3331-4001
	Ali Al-Masoudi, 4.3
	Erik Benkler, 4.3, https://orcid.org/0000-0001-7907-849X
	Thomas Legero, 4.3, https://orcid.org/0000-0003-0277-3907
	Uwe Sterr, 4.3, https://orcid.org/0000-0001-5661-769X
	Stefan Weyers, 4.4, https://orcid.org/0000-0003-4484-6481
	Johannes Rahm, 4.4, https://orcid.org/0000-0002-4832-8043
	Burghard Lipphardt, 4.4
	Christian Lisdat, 4.3, https://orcid.org/0000-0002-4705-8854
Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig, Germany


License:
CC BY-ND 4.0 (Creative Commons Attribution-NoDerivatives 4.0 International Public License)

Keywords: 
Optical clocks ; Primary frequency standards ; Absolute frequency measurement ; Clock stability

Classification:
INSPEC A3200 Atomic spectra and interactions with photons ; INSPEC A3280P Photon interactions with atoms ; INSPEC A4262 Laser applications

Funder:
We acknowledge support by the project 18SIB05 ROCIT, which has received funding from the EMPIR programme cofinanced by the Participating States and from the European Union’s Horizon 2020 research and innovation programme, and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy—EXC-2123 Quantum Frontiers—390837967 and CRC 1228 DQ-mat within project B02. This work was partially supported by the Max Planck-RIKEN-PTB Center for Time, Constants and Fundamental Symmetries. 

Description of the individual files:
The data sets 'Sr_instab_1.dat' and 'Sr_instab_2.dat' provide time series of fractional frequency differences of the offset frequencies between the atomic frequency and the interrogation laser's reference cavity of two stabilizations interleaved in time. From them, the Allan deviations in Fig. 1 in the publication can be calculated. 'Sr_instab_1.dat' corresponds to the ADEV 'self-comparison (Si 2)', 'Sr_instab_2.dat' to 'self-comparison (Si 2+3, avg.)'. The time interval for both data sets is 13.52 s.

Files 'Sr_vs_CSF1.dat' and 'Sr_vs_CSF2.dat' contain data related to Tab. II and Fig. 3. The columns give 
	the date in MJD as assigned in Tab. II of the publication, 
	the centre of gravity in UTC of the Sr clock uptimes for the interval described in this line of the file, 
	the start, end, and centre of the interval on which the fountain - maser frequency ratio was averaged in UTC, 
	the length of the included Sr data in seconds,
	the fractional systematic uncertainty of the Sr clock in 1E-16,
	the fractional extrapolation uncertainty in 1E-16,
	the length of the Cs fountain averaging interval in days,
	the fractional statistical and systematic uncertainty from the fountain assigned to this interval in 1E-16,
	the last digits and the uncertainty of the Sr transition frequency in Hz as evaluated on the interval,

The time traces used to calculate the instabilities/ADEVs of the maser as measured by the more stable Sr lattice clock (Fig. 2 in the publication) are given in the files '2017-01-30_H10.dat', '2018-04-20_H9.dat', '2018-11-19_H9.dat', and '2019-07-08_H9.dat'. Data are given on a 1 s grid and represent the Sr clocks frequency in Hz as measured by the maser minus a constant offset for each data set. To correctly account for down times in the measurements, invalid data intervals are displayed as '0.000000'. 



