Results from the PolarquEEEst missions

Marcello Abbrescia and the airship – 1928

A scientific mission to the Aldo Pontremoli The Preparation and Scientific Results of the Italia Polar Expedition

Umberto Nobile, Mondadori, Milano, 1938

František Běhounek Why Cosmic rays at the North Pole?

At the beginning of last century it was believed that cosmic rays were high-energy neutral particles (i.e. gamma rays)  no effect from the Earth’s magnetic field on cosmic ray flux

Then observation of the dependence of the corsmic ray flux on latitude  cosmic rays are mainly charged particles

The geomagnetic field swipes away low energy charged cosmic rays with an energy threshold depending on latitude  interest in measuring the cosmic ray flux close to the Poles

4 The trip

The Polarquest2018 expedition started on board the boat Nanuq on July 22, 2018 from Isafjordur and ended in Tromso on September 3.

Some experiments were hosted on board the boat, about:

Mapping of unchartered zones in north Measurements of concentration of microplastics in the Polar sea water Measure of cosmic rays vs. latitude (PolarquEEEst2018): - 1 detector on board Nanuq (POLA-01) - 2 detectors at Nessoden (Oslo) (POLA-02) and Bra (TO) (POLA-03)

5 Requirements for the PolarQuEEEst detector

The Detector on the Polar Nanuq was designed to fulfill requests on:

- Dimensions and weight (~ 50 kg) - Power consumption (< 15 W) - Robustness and reliability - Efficiency - Tag events at 20 ns precision Design of PolarQuEEEst detector

2 Plastic scintillator planes

Distance between planes: 11 cm

4 Tiles for each plane: 30 cm x 20 cm

2 SiPMs per tile (16 SiPMs in total) The PolarQuEEEst detector electronics

(overall power consumption:12-13 W)

Power box Back-up Battery

GPS GNSS-Ublox Readout board FPGA Altera Cyclone 5 For Trigger and TDC readout Sense Hat Gyroscope Accelerometer Magnetometer Temperature Barometric pressure HPTDC piggy-back Humidity for TDC readout

Raspberry PI Control readout  Data stored on SSD memory GPS or transmitted GNSS-Ublox via internet

8 The PolarQuEEEst prototype during tests

Prototypes box and Detector during assembling scintillators

A 4 x 4 mm2 Silicon Photomultiplier The PolarQuEEEst prototype, with the team who has just built it Assembling

Performed at CERN by high schools students form , Switzerland and

24 May 2018 ≥ 3 SiPMs coincidence required  Single POLA rate ≈ 30 Hz

Tests at CERN

POLA-01 POLA-02 POLA-03

CERN-01

CERN-02

11 Installation All the detectors installed by the end of July 2018

POLA-02 @ Oslo POLA-01 @ Isafjordur (Nesodden)

POLA-03 @ Torino POLA-01 on board (Bra) Nanuq leaving Isafjordur (Iceland)

13 Nanuq en route to the Svalbard archipelago PolarquEEEst2018 Statistics

Trip length Nanuq sailed for 45 days covering about 3500 NM

Duty cycle The POLA-01 cosmic ray detector has taken data almost continuously for about 984 hours

Detector efficiencyData Analysis - for POLA-01: about 91% efficiency due to various reasons (main power down, difficult weather conditions, detector reset …. )

- for POLA-02 and POLA-03: essentially 100% efficiency (they were functioning during the whole period)

Collected muons In total, more than 100.000.000 muon tracks per detector were collected Rate (uncorrected)

16 Corrections 1. Rates have to be corrected for the barometric effect since the absorption of secondary cosmic rays increases with the amount of matter in the atmosphere, to which the pressure is proportional  corrections obtained by fitting the rate dependence on the pressure for each detector separately during the full period

2. For POLA-01 also correction due to the detector orientation which may change when sailing (less relevant than pressure correction)  corrections obtained by correlating the rate with the azimuthal angle using the accelerometer installed in the station (z-projection of the acceleration, 1 means vertical direction, i.e. gravity)

17 Orientation correction On 30 July a problem occurred for Nanuq (during low tide) …

Data were nevertheless collected before reaching this “exotic” position

This special event allowed to verify the proper calibration of the orientation correction !!

18

Rate (corrected)

20 POLA-02 (in Oslo @ 59° N) used as reference since Rate vs. latitude closer in latitude than POLA-03 (in Turin @ 45° N)

No significant effect observed  possible variation < 1%

82° N (max) – North of Svalbard

POLA-01 on Nanuq

66° N (min) - Iceland 21 Uncorrected rate during the trip

22 Corrected rate during the trip

23 Previous cosmic ray measurements at sea level

A.H. Compton Phys. Rev. 43 (1933) 387

… vs. latitude

Polar Ship Survey, 1999

… on boat

Soya Ship Route, 1960 24 Comparison with theory and previous measurements (Northern Canada & Alaska) (Svalbard)

Ions/cc s G. Lemaître, in standard air M.S. Vallarta theory Phys. Rev. 42 (1932) 914

A.H. Compton Phys. Rev. 43 (1933) 387

 Southern hemisphere — O Northern hemisphere 2 Compton + Millikan (Pasadena) x boat from Genoa to Singapore PolarquEEEst 2018 The PolarquEEEst journey

At the end of 2018 and in 2019 the POLA-01 detector started a trip across Italy and Germany to cover an increased range in latitude

Location Date Latitude Nanuq Jul 22-Sep 4 2018 66°05′-82°06′ Genova Oct 25 2018 44°24′ Vigna di Valle (Rome) Nov 27 2018 42°04′ Cosenza Dec 3-4 2018 39°18′ Messina Dec 5 2018 38°11′ Cefalù (Palermo) Dec 6 2018 38°02′ Erice ( 900m a.s.l., Trapani) Dec 6-8 2018 38°02′ Catania-Etna Dec 12-Feb 15 37°30′ (Catania, ≈ 2000 m a.s.l.) Lampedusa Mar 6-15 2019 35°30′ Bologna Apr 3-4 2019 44°29′ Munich Apr 10 2019 48°08′ Hannover Apr 10-11 2019 52°22′ Frankfurt am Main Apr 11-12 2019 50°06′ CERN Apr 12-May 2 2019 46°12′ Corrected rate vs. latitude PolarquEEEst 2019: EEE@NyAlesund First long term study of the high energy cosmic rays flux with charged particles at sea level and at the northernmost latitudes

 Three detectors installed in May 2019 at Ny Alesund: a mini- array for Extensive Air Showers  Events at each detector tagged in time

Goals:  Cosmic rays physics at high latitudes (where very few measurements exist): monitoring the Solar cycle  Study of possible correlations of cosmic rays flux with atmospheric conditions (interesting for climate change)  Benefit from measurements on atmoshpere performed at Ny Alesund Locations for the PolarquEEEst 2019 detectors Ideally, stations should be ≈ 5-600 m from each other, to allow to triangulate on the shower arrival direction POLA-01: small hut at the Amundsen-Nobile climate tower POLA-03: Dirigibile Italia CNR station POLA-04: Gruvebadet laboratory -Note: POLA-02 is an indentical reference detector operating at Nessoden (Oslo) Map of locations @ Ny Alesund

POLA-01 POLA-03

POLA-04

POLA-02 remains at Nessoden as a reference station in controlled conditions PolarquEEEst 2019 laboratories

Gruvebadet laboratory First coincidences (very preliminary!)

Amundsen-Nobile climate change tower

Dirigibile Italia station Data analysis Data already available on the usual EEE website: eee.centrofermi.it/monitor through the usual data request form

Available for analysis SIF prima pagina An article already appeared in the last issue: EEE goes back to the North Pole

The news also appeared on Universities, Schools websites and newspapers . Thanks to PolarQuEEEst EEE

 Precision study of the cosmic ray intensity at high latitudes up in the Artic polar region where no published data exist

 Check of the saturation of the cosmic ray intensity (suppression of the low-energy intensity) at higher latitudes

 Very useful probe to understand the configuration of the cosmic ray energy spectrum affected by the Sun activity

34 Data analysis Data already available on the usual EEE website: eee.centrofermi.itThe Polarqu/monitor throughEEE stthe usual missions data request form

Extremely Exciting Experiences