Research Areas

The PERSEVERANCE hosted the first muon detector developed in June 2023.

CosmicSail on board the Perseverance has two objectives:

– Educational: Raising awareness about cosmic particle physics and introducing the scientific method

– Scientific: To complete knowledge of muon dynamics over the oceans by highlighting the phenomena that modulate their variation and using models. To achieve this, design and produce muon detectors and install them on volunteer sailing vessels, which has never been done before.

Muon detector on the bridge of the PERSEVERANCE

First measurements starting in 2023

The number of detections shows an increasing trend from Marseille to Spitsbergen. This increase could be influenced by various factors such as the pressure effect, which is anti-correlated, the latitude effect, which is correlated, and the air temperature effect. Detection peaks were recorded during the evenings of 07/02 and 07/05, while minimums were observed on 06/24, 07/04, and 07/06. Muons are detected by a current (in mV) generated at the silicon photomultiplier (SiPM), with the signal amplitude depending on the muon’s energy. The majority of detections are between ~500 and 700 mV, and between ~800 and 1200 mV, with values of 3,000 mV or more recorded in rarer cases. The increase in the number of detections from Marseille to Spitsbergen affects the entire energy spectrum of detected muons, but is more pronounced for detections exceeding 1,000 mV.

In summary, the number of muon detections shows a slight increase from Marseille to Spitsbergen, influenced by several parameters such as pressure, latitude, solar activity, and air temperature. Pressure variations appear to follow the expected trend of anti-correlation with the number of detections, but this trend must be confirmed over a longer period, particularly during extreme events such as deep depressions. The number of detections increases with latitude, but it is necessary to determine what portion of these variations is due to changes in latitude, using an appropriate model.

Example of measurements by the muon detector installed on the bridge of the PERSEVERANCE. Left: (top, in gray) hourly averages of counts/minute of muons. In bold blue: 12-hour moving average. (middle) air temperature hourly data from the onboard Météo France station (bottom) atmospheric pressure hourly data from the muon detector’s pressure sensor. Right: hourly average of the number of counts/minute along the PERSEVERANCE’s route from 06/16 to 09/20.

Regarding solar activity, a downward trend in the number of detections was observed during the identified events. However, the effect may vary depending on the type of solar storm, thus requiring additional data over a prolonged period, particularly during more intense solar storms. The number of detections is also strongly correlated with the temperature measured by the sensor. A comparison with the outside air temperature will make it possible to distinguish variations due to natural diurnal temperature fluctuations, known to be correlated with muon production, from those caused by variations in the sensor temperature.