Open data from the third observing run of LIGO, Virgo, KAGRA, and GEO

The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in 2019 April and lasting six months, O3b starting in 2019 November and lasting five months, and O3GK starting in 2020 April and lasting two weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main data set, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages

Radon anomalies preceding earthquakes which occurred in the UK, in summer and autumn 2002

During the course of an investigation into domestic radon levels in Northamptonshire, two hourly sampling real-time radon detectors were operated simultaneously in separate locations 2.25 km apart in Northampton, in the English East Midlands, for a 25-week period. This period of operation encompassed the period in September 2002 during which the Dudley earthquake (magnitude – 5.0) and smaller aftershocks occurred in the English West Midlands, UK. We report herein our observations regarding the occurrence of simultaneous short-period radon anomalies and their timing in relation to the Dudley, and other, earthquakes which occurred during the monitoring period. Analysis of the radon time-series reveals a short period when the two time-series displayed simultaneous in-phase short-term (6–9 h) radon anomalies prior to the main Dudley earthquake. Subsequent investigation revealed that a similar period occurred prior to another smaller but recorded earthquake in the English Channel

Identification of tidal and climatic influences within domestic radon time-series from Northamptonshire, UK

Analysis of data from extended radon concentration time-series obtained from domestic and public-sector premises in the vicinity of Northampton, UK, and elsewhere, confirms that, in addition to the generally recognised climatic influences, ‘Earth Tides’ and ‘Ocean Tidal Loading’ drive periodic radon liberation via geophysically driven groundwater level variations. Regression and cross-correlation with environmental parameters showed some degree of association between radon concentration and mean temperature and rainfall. Fourier analysis of radon time-series identified periodicities of the order of 23.9 h (luni-solar diurnal, K1), 24.0 h (solar day, S1), 168 h (1 week) and 661.3 h (lunar month, Mm), while cross-correlation with tidal strength demonstrated periodicity of the order of 14 days (lunar–solar fortnight, Mf). These results suggest that astronomical influences, including tides, play a part in controlling radon release from the soil

Tidal synchronicity of built-environment radon levels in the UK

In our recent work on radon in UK homes the authors have observed tidal-periodic variations in built-environment radon levels and here report results from our ongoing investigations. These tidal variations have been quantified using a variety of analytical techniques, including a novel correlation technique developed as part of this investigation. The observed variations are cyclic at the 14-15 day tidal period and lag new/full moons by varying periods of days, the magnitude of the variation and lag being dependent on factors such as location, underlying geology and rock/soil hydration. As well as quantification and discussion of tidal effects on radon levels, the potential effects of such phenomena on the reliability of short-term radon measurements are discussed

The value of Seasonal Correction Factors in assessing the health risk from domestic radon - a case study in Northamptonshire, UK

Following an intensive survey of domestic radon levels in the United Kingdom (UK), the former National Radiological Protection Board (NRPB), now the Radiation Protection Division of the Health Protection Agency (HPA-RPD), established a measurement protocol and promulgated Seasonal Correction Factors applicable to the country as a whole. Radon levels in the domestic built environment are assumed to vary systematically and repeatably during the year, being generally higher in winter. The Seasonal Correction Factors therefore comprise a series of numerical multipliers, which convert a 1-month or 3-month radon concentration measurement, commencing in any month of the year, to an effective annual mean radon concentration. In a recent project undertaken to assess the utility of short-term exposures in quantifying domestic radon levels, a comparative assessment of a number of integrating detector types was undertaken, with radon levels in 34 houses on common geology monitored over a 12-month period using dose-integrating track-etch detectors exposed in pairs (one upstairs, one downstairs) at 1-month and 3-month resolution. Seasonal variability of radon concentrations departed significantly from that expected on the basis of the HPA-RPD Seasonal Correction Factor set, with year-end discontinuities at both 1-month and 3-month measurement resolutions. Following this study, monitoring with electrets was continued in four properties, with weekly radon concentration data now available for a total duration in excess of three and a half years. Analysis of this data has permitted the derivation of reliable local Seasonal Correction Factors. Overall, these are significantly lower than those recommended by HPA-RPD, but are comparable with other results from the UK and from abroad, particularly those that recognise geological diversity and are consequently prepared on a regional rather than a national basis. This finding calls into question the validity of using nationally aggregated Seasonal Correction Factors, especially for shorter exposures, and the universal applicability of these corrections is discussed in detail

The practical use of electrets in a public health radon remediation campaign

As part of a long-term assessment of domestic radon in Northamptonshire, England, a batch of 50 commercially available electrets was deployed for nearly 1000 exposures, individual exposure periods ranging from one to eight weeks. Responsivity was comparable with that of recently-calibrated Durridge RAD-7 continuously-monitoring equipment. Voltage history analysis indicated mean voltage decay during manufacturers' QA assessment of 0.059 ± 0.026 V day−1, increasing to 0.114 ± 0.073 V day−1 during storage to first use and to 0.204 ± 0.49 V day−1 during inter-deployment storage. At a representative elevated radon concentration of 500 Bq m−3, the resulting perturbation is 3% over a 7-day deployment; at the typical mean Northamptonshire level of 80 Bq m−3 it approaches 22%. Each electret can be used for up to 25 measurements, which makes the technology attractive for organisational use. It is not suited for deployment by individual householders