Data blinding for the nEDM experiment at PSI

N. J. Ayres, G. Ban, G. Bison, K. Bodek, V. Bondar, E. Chanel, P. J. Chiu, C. B. Crawford, M. Daum, S. Emmenegger, L. Ferraris-Bouchez, P. Flaux, Z. Grujić, P. G. Harris, N. Hild, J. Hommet, M. Kasprzak, Y. Kermaïdic, K. Kirch, S. KomposchA. Kozela, J. Krempel, B. Lauss, T. Lefort, Y. Lemiere, A. Leredde, P. Mohanmurthy, A. Mtchedlishvili, O. Naviliat-Cuncic, D. Pais, F. M. Piegsa, G. Pignol, M. Rawlik, D. Rebreyend, I. Rienäcker, D. Ries, S. Roccia, D. Rozpedzik, P. Schmidt-Wellenburg, A. Schnabel, R. Virot, A. Weis, E. Wursten, J. Zejma, G. Zsigmond

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Psychological bias towards, or away from, prior measurements or theory predictions is an intrinsic threat to any data analysis. While various methods can be used to try to avoid such a bias, e.g. actively avoiding looking at the result, only data blinding is a traceable and trustworthy method that can circumvent the bias and convince a public audience that there is not even an accidental psychological bias. Data blinding is nowadays a standard practice in particle physics, but it is particularly difficult for experiments searching for the neutron electric dipole moment (nEDM), as several cross measurements, in particular of the magnetic field, create a self-consistent network into which it is hard to inject a false signal. We present an algorithm that modifies the data without influencing the experiment. Results of an automated analysis of the data are used to change the recorded spin state of a few neutrons within each measurement cycle. The flexible algorithm may be applied twice (or more) to the data, thus providing the option of sequentially applying various blinding offsets for separate analysis steps with independent teams. The subtle manner in which the data are modified allows one subsequently to adjust the algorithm and to produce a re-blinded data set without revealing the initial blinding offset. The method was designed for the 2015/2016 measurement campaign of the nEDM experiment at the Paul Scherrer Institute. However, it can be re-used with minor modification for the follow-up experiment n2EDM, and may be suitable for comparable projects elsewhere.

Original languageEnglish
Article number152
JournalEuropean Physical Journal A
Issue number4
StatePublished - Apr 2021

Bibliographical note

Funding Information:
We gratefully acknowledge financial support from the Swiss National Science Foundation through project grants 149211, 162574 and 172639 for the ETHZ group, grant 181996 for the Bern group and grants 117696, 144473, 137664, 163413, 169596, and 171626 for the PSI group. This work was funded in part by the United Kingdom Science and Technology Facilities Council (STFC) through grants ST/N000307/1 and ST/M503836/1, as well as by the School of Mathematical and Physical Sciences at the University of Sussex. One of the authors (P. M.) would like to acknowledge support from the Swiss State Secretariat for Education, Research and Innovation (SERI) - Federal Commission for Scholarships (FCS) award #2015.0594. We likewise gratefully acknowledge financial support from the Polish National Science Center, through grants UMO-2015/18/M/ST2/00056, UMO-2016/23/D/ST2/00715 and UMO-2018/30/M/ST2/00319. We are most grateful for the excellent support provided by the PSI technical groups and by various services of the collaborating universities and research laboratories.

Publisher Copyright:
© 2021, The Author(s).

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


Dive into the research topics of 'Data blinding for the nEDM experiment at PSI'. Together they form a unique fingerprint.

Cite this