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Measuring the cosmic radiation at different altitudes ; an educational trip

Measuring the cosmic radiation at different altitudes ; an educational trip. F.Riggi , 8° Conferenza dei Progetti del Centro Fermi, Erice, 6-8 Dicembre 2017. Theodor Wulf experiment.

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Measuring the cosmic radiation at different altitudes ; an educational trip

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  1. Measuring the cosmicradiationatdifferentaltitudes; an educational trip F.Riggi, 8° Conferenza dei Progetti del Centro Fermi, Erice, 6-8 Dicembre 2017

  2. Theodor Wulf experiment March 30, 1910: Theodor Wulf, a germanphysicist and jesuitpriestisbringinghiselectroscope up to the Eiffel Tour, to perform air ionizationmeasurements. Why the Eiffel Tour? Actually, he hadalreadydonemeasurements in differentplaces (mountains, mines, caves) with variableresults. So, again, why the Eiffel Tour and notmountains? Theodor Wulf (1868-1946) Wulf, Theodor (1910). "Observations on the radiation of high penetration power on the Eiffel tower". PhysikalischeZeitschrschift. 11: 811.

  3. Theodor Wulf experiment Eiffel Tower: the tallest building atthat time… about 300 m … but with just a moderate shieldingbelowit… In otherwordshis goal was: Going far from groundratherthancloser to the sky The experimentalresultactuallywasthat a slightlysmaller (nothigher!) radiationwasmeasuredat the top with respect to ground… Averages: 17.9 Ground 15.7 Top Wulf originalresults

  4. Theodor Wulf experimentreanalyzed Observedvalueatground Observedvalue on the Eiffel Tour (300 m) How to interpretthisresult? Radiationemitted from rocks (due to radioactivity) wasalreadyknownat the time. Expecteddecrease of radiationas due to gamma absorption in air The valueobtainedat 300 m wassmallerthanatground, butlargerthanexpected, and isinfluenced by an additionalradiationcoming from above.

  5. Hess and balloon flights • In the sameyears, an austrianphysicist - Victor Hess - becameinterested in the problem of air ionization, reconsidering the results by Wulf: • Thesecould be due to twocauses: • 1) Absorption of gamma rays in air could be muchsmaller • 2) Anotherionizing source could be active in the atmosphere • The absorption of gammas from Radium C (Bi214) in air was first studied by Hess with greaterprecision. • Under the hypothesis of a uniformdistribution of RaC on the Earth itwascalculatedthatat 1000 m the radiation from Earth should reduce to 0.1% of the groundvalue. • To understand the results from Wulf and make quantitative measurements Hess decided to use electroscopesduring balloon flights. • Several balloon flightswereorganized: Victor Hess (1883-1964) 2 in 1911 7 in 1912 1 in 1913

  6. Hess and balloon flights On August 7th 1912 a decisive flight, up to 5350 m, brougth to a firmevidencethatafter an initialdecrease with height, the ionizationstarted to increaseagain, demonstrating the extra-terrestrialorigin of thisradiation. No differencebetween night and daywasobserved. In 1936 Hess received the Nobel Prize for «hisdiscovery of the cosmicradiation»

  7. Hess and balloon flights Results from Hess measurements with balloon flightsweresoonconfirmed by otherexperimenters

  8. High altitudelaboratories Systematicinvestigation of the cosmicrayfluxwasthencarried out at high altitudes with permanentinstallations on the top of severalmountains, by Hess and later by manyotherphysicists, tilltoday. Hess laboratory, near Innsbruck, at 2300 m (1932)

  9. High altitudelaboratories Just a fewexamples.. Picdu Midi (Pirenei), 2887 m Jungfraujoch (Svizzera), 3454 m Chacaltaya (Ande, Bolivia), 5230 m

  10. Hess life and legacy Hess life wasnot easy.. Surviving to amputation of hisleftthumb and surgery for a larynx carcinoma in 1934, aftergetting the Nobel Prize in 1936, Austria wasoccupied in 1938 by Germany and he wasarrested for a short period. Accused to be a believingcatholic (actuallyhiswifewasJewish), and against the National Socialism, he wasdismissed from hisacademic position, and losteverything, includinghispension. In 1938, he and hiswifeemigrated to the US, where he got a position atFordhamUniversity in New York. He did go on with research on radiationsevenafterhisretirement in 1958.

  11. Extensive air showers in the atmosphere

  12. Extensive air showers in the atmosphere 15-20 km Sea level

  13. Extensive air showers in the atmosphere Most of cosmicshowers are initiated in the upper part of the atmosphere COSMOS calculations

  14. Altitudedependence Electron and muonfluxatdifferentaltitudes: COSMOS calculations

  15. Altitudedependence Quantitative measurements of the altitudedependence of the cosmicrayfluxcarried out for the variouscomponents (muons, electrons,…)

  16. Educational measurements Measurements of the cosmicrayfluxatdifferentaltitudes are a powerful educational tool and may be carried out with different detectors Count rate measuredduringtwo commercial flights (CT-MI) as a function of the time elapsed from take-off Count/minute Count/minute Altitude (m) Count rate measured with portable Geiger countersduring a trip to Mount Etna by a school team in Catania. Time from take-off (min)

  17. The role of detectors Geiger counters are sensitive to chargedparticles (cosmicmuons and electrons) with a high efficiency, butalso – eventhough a small efficiency – to gamma radiationsoriginating from ground. Possiblesolutionwhenoperating with Geiger counters: Insert a heavy metal shieldbelow the Geiger (Lead, Iron,..)

  18. The role of detectors Alternative solution: Use two detectors in coincidence (telescopeconfiguration), as the COSMIC BOX Cosmicmuons (penetratingparticles) pass easilythrough the two detectors Gammas and lowenergyparticles from below are notable to givesignals in both detectors, so they do notcontribute to the collectedevents

  19. Ourexperimenttomorrow Measure the cosmicrayflux with severalCosmic Box detectors at 3 differentaltitudes: Near Trapani, sealevel ( 0 m ) Segesta (350 m) Erice (750 m)

  20. Ourexperimenttomorrow Statistical considerations Due to geometricalsize of detectors and their mutualdistance, the expectedcoincidence rate is of about 0.5 Hz Expectednumber of counts in 30’: 30x60x0.5 = 900 Summing data from 15 detectors: 900x15 ~13000 counts Statistical error (from Poissondistribution) = √N Relative error = √N / N √N √N / N For a single detector (N=900) 30 3.3 % For 15 detectors (N=13500) 116 0.9 % With 15 detectors weshould be able to seevariations of a fewpercent

  21. Ourexperimenttomorrow Statistical considerations Due to geometricalsize of detectors and their mutualdistance, the expectedcoincidence rate is of about 0.5 Hz Expectednumber of counts in 30’: 30x60x0.5 = 900 Summing data from 15 detectors: 900x15 ~13000 counts Statistical error (from Poissondistribution) = √N Relative error = √N / N √N √N / N For a single detector (N=900) 30 3.3 % For 15 detectors (N=13500) 116 0.9 % With 15 detectors weshould be able to seevariations of a fewpercent ENJOY THE TRIP!

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