Cosmic Ray Physics. An Introduction to the Cosmic Laboratory

324 Pages·2023·57.411 MB·English

by  Veronica Bindi, Mercedes Paniccia, Martin Pohl

Cosmic Ray Physics
This book introduces you to the physics of cosmic rays, charged particles which reach
us from known – and maybe unknown – sources in the cosmos. Starting from a brief
history of this fascinating field, it reviews what we know about the creation of elements
in the Big Bang and inside stars. It explains cosmic accelerators reaching fabulous ener-
gies. It follows the life cycle of cosmic rays all the way from their sources to detection
near, on or below Earth. The central three chapters cover what we know about them at
the level of the solar system, the Milky Way and the Universe at large. Up-to-date exper-
imental results are presented in detail, showing how they are obtained and interpreted.
The book provides an accessible overview of this lively and diversified research field.
It will be of interest to undergraduate physics students beginning their studies on as-
tronomy, cosmology, and particle physics. It is also accessible to the general public by
concentrating mathematical and technical detail into Focus Boxes.
Cosmic Ray Physics
An Introduction to the Cosmic Laboratory
Veronica Bindi
Mercedes Paniccia
Martin Pohl
Image Credit: NASA
First edition published 2023
by CRC Press
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and by CRC Press
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CRC Press is an imprint of Taylor & Francis Group, LLC
© 2023 Veronica Bindi, Mercedes Paniccia and Martin Pohl
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sume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have
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ISBN: 978-1-032-00391-7 (hbk)
ISBN: 978-1-032-02001-3 (pbk)
ISBN: 978-1-003-18138-5 (ebk)
DOI: 10.1201/9781003181385
Typeset in CMR10
by KnowledgeWorks Global Ltd.
Publisher’s note: This book has been prepared from camera-ready copy provided by the authors.
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En algu´n lugar debe haber un basural donde est´an amontonadas las explicaciones.
Una sola cosa inquieta en este justo panorama: lo que pueda ocurrir el d´ıa en que alguien
consiga explicar tambi´en el basural.1
Julio Cort´azar, Un Tal Lucas [260]
1Somewheretheremustbeagarbagedumpwheretheexplanationsarepiledup.Thereisonlyoneworry
inthisfairscenario:whatmighthappenthedaysomeonemanagestoexplainalsothedump.
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Taylor & Francis
Taylor & Francis Group
http://taylorandfrancis.com
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Contents
Preface...............................................................................................................................ix
Authors..............................................................................................................................xi
Chapter 1 Cosmic Rays and Us...................................................................................1
1.1 Distance, time and energy...................................................................5
Chapter 2 A Brief History...........................................................................................9
2.1 Air electricity......................................................................................9
2.2 Early pioneers...................................................................................10
2.3 Up and away.....................................................................................12
2.4 Images of cosmic rays........................................................................19
2.5 Extensive air showers........................................................................27
2.6 The Cosmic Laboratory....................................................................36
Chapter 3 Gross Features..........................................................................................49
3.1 Observables and techniques..............................................................49
3.2 Particle spectra and composition......................................................55
Chapter 4 Particle Production...................................................................................63
4.1 Big Bang nucleosynthesis..................................................................63
4.2 Up to iron.........................................................................................66
4.3 Beyond iron.......................................................................................75
4.4 Dark Matter......................................................................................77
4.5 Astrophysical antimatter...................................................................85
4.5.1 Secondary positrons...............................................................86
4.5.2 Pulsar positrons.....................................................................87
4.5.3 Secondary antiprotons...........................................................88
Chapter 5 Cosmic Accelerators..................................................................................93
5.1 Fermi acceleration.............................................................................93
5.2 Supernovae........................................................................................99
5.3 Winds...............................................................................................102
5.4 Jets...................................................................................................104
Chapter 6 Particle Transport....................................................................................109
6.1 Galactic properties...........................................................................109
6.2 Diffusion...........................................................................................112
6.3 Interactions......................................................................................118
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viii Contents
Chapter 7 Pointing Messengers.................................................................................121
7.1 Photons............................................................................................121
7.2 Neutrinos.........................................................................................131
Chapter 8 In the Heliosphere....................................................................................139
8.1 The Sun...........................................................................................139
8.2 Sunspots and solar cycles.................................................................141
8.3 The solar wind and the Sun’s magnetic field...................................144
8.4 Heliospheric Magnetic Field Structure.............................................147
8.5 Global Heliosphere Structure...........................................................149
8.6 Solar Modulation.............................................................................150
8.7 Transient Phenomena in the Solar Wind.........................................157
8.7.1 Interplanetary Coronal Mass Ejections................................158
8.7.2 Corotating interaction regions..............................................160
8.7.3 Forbush Decreases................................................................161
8.8 Solar flares and solar energetic particles..........................................163
8.9 The Earth’s Magnetosphere.............................................................167
8.9.1 Radiation Belts.....................................................................169
8.9.2 Magnetospheric Current Systems.........................................171
8.10 Space Weather Physics.....................................................................172
8.10.1 Magnetic Storms and Substorms..........................................173
Chapter 9 In the Milky Way.....................................................................................177
9.1 Models confronting observations......................................................177
9.2 Space detectors................................................................................181
9.3 Cosmic nuclei...................................................................................188
9.3.1 Protons and helium..............................................................188
9.3.2 Light nuclei...........................................................................196
9.3.3 Heavy nuclei.........................................................................203
9.3.4 Isotopes................................................................................213
9.4 Nuclear antimatter...........................................................................216
9.5 Strangelets.......................................................................................219
9.6 Electrons and positrons....................................................................219
Chapter 10 In the Cosmos..........................................................................................227
10.1 Extensive air showers.......................................................................229
10.2 Air shower observatories..................................................................235
10.3 Knees...............................................................................................243
10.4 Ankle................................................................................................245
10.5 Anisotropies.....................................................................................246
10.6 Extragalactic sources.......................................................................249
Chapter 11 The Next Revolution...............................................................................253
11.1 Direct detection...............................................................................253
11.2 Ultra-high energies...........................................................................257
11.3 Multiple messengers.........................................................................260
Bibliography.................................................................................................263
Index.............................................................................................................305
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Preface
The stars began to crumble and a cloud of fine stardust fell through space.
James Joyce, A Portait of the Artist as a Young Man [306, p. 87]2
My first encounter with cosmic ray physics was Bruno Rossi’s book “Cosmic Rays” [169]
which I read when I was an undergraduate student in the 1970s. I consulted it because –
in contrast to other authors – in this and his previous more general book [141], Rossi did
not shy away from discussing experimental techniques and their influence on the quality of
physics results. No wonder, since Rossi at MIT was one of the inventors of the coincidence
technique,whichhelpedconvertingamostlyanecdotalwayofstudyinghigh-energyparticles
intoasystematicscience.Duringthisperiod,cosmicraysalsoceasedtobetheprimesource
of high-energy particles. Accelerators and later colliders provided controllable conditions
to study particle production and interactions. Instead, cosmic rays became themselves a
subject of research, as messengers from the cosmic laboratory.
In later years as a post-doc, I occasionally (mis-)used collider detectors at PETRA
(DESY, Germany) and LEP (CERN, Switzerland), suitably modified, to make on-ground
and underground measurements of cosmic muons, the penetrating heavy component of air
showers caused by cosmic rays in the atmosphere. But it was only by the year 2000 that
I got seriously involved in a dedicated cosmic ray experiment, when I learned about the
successfulflightoftheprototypeAlphaMagneticSpectrometer(AMS-01)onSpaceShuttle
Discovery in 1998. I joined the collaboration constructing the final version of the detector,
installedontheInternationalSpaceStationin2011.Atthetime,Ithoughtthatthiswould
beatemporaryinvolvement,whilewaitingfortheLargeHadronCollideratCERNtostart
up. But it turned out to keep me busy for the rest of my professional life.
Constructing particle physics instruments for the use in space is a challenging task.
Not only are there tough mechanical conditions during the rough ride on a rocket. The
environmentinorbitisevenmoredemanding,asfarastemperatureexcursionsandradiation
levels are concerned. Running and analysing space experiments over extended periods is
equally challenging. Occasions for repair are rare or inexistent, in-orbit calibration and the
tracking of varying conditions are complex tasks. However, as recent experiments on free-
flying satellites and on the ISS show, these difficulties can be overcome such that particle
physics in space reaches statistical and systematic accuracy similar to standards set by
accelerator experiments.
Dothesedatamakesenseintermsofparticlephysics?Canacompletepictureofcosmic
rays from their production to their detection near Earth be constructed? And most impor-
tantly, do we know all their sources? The answer is probably “not quite yet”, there is no
standard model of cosmic rays. But the current status of interpreting high quality cosmic
rays data is still worth describing. This is the purpose of this book. It wants to get you on
the hook, just as Rossi’s book got me on the hook 50 years ago. Thus one of its baits is to
go into details about the experimental methods that lead to high quality data. And it will
also not gloss over things we do not understand, so that you can drive (or at least follow)
further progress in the field.
Iwantyou,thereader,todecidewhatlevelofdetailyouwishtoexplore.Ihavethussep-
arated the text into a continuous narrative, with only as much mathematical and technical
detail as necessary, and Focus Boxes, which provide just these details basically at textbook
level.Acommonjokeaboutthisapproachisthatallargumentswhichrequiremathbeyond
2QuotedbypermissionfromOxfordUniversityPress.
ix
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x Contents
the rule of three are relegated to boxes. To fully appreciate their contents, it will probably
be useful to have some background in modern particle physics. However, these notions are
accessibly described in standard introductory textbooks on nuclear and particle physics, or
in online courses like the one by Mercedes Paniccia and me.3
The three Chapters 8 to 10 are the heart of this book. Chapter 8 has been written by
VeronicaBindi,describingradiationcomingfromourSunandwhathappenstocosmicrays
inside the heliosphere. Help with this chapter by Cristina Consolandi from University of
Hawaii is gratefully acknowledged. Chapter 9 covers latest results on galactic cosmic rays
andwhathasbeenlearnedfromthemsofar.IthasbeencontributedbyMercedesPaniccia.
Chapter 10 has been written by me, even though its subject is a little outside my field
of experience. I am very grateful to Bill Hanlon from University of Utah for spotting the
flaws in the first draft of this chapter. Thanks are also due to Friedrich-Karl Thielemann
forpreciousadviceonthecomplexnuclearphysicsinChapter4.CarlosMan˜aBarrerafrom
CIEMAT Madrid has been kind enough to review the first complete draft. He found many
mistakes I should have spotted myself, thus sparing me a fair amount of embarrassment.
I wish to thank my co-authors for their patience and the many colleagues I consulted
for the invaluable help and encouragement I received. Without them, there would be even
more errors and misconceptions in this book than you will doubtlessly identify.
Martin Pohl
October, 2022
3https://www.coursera.org/learn/particle-physics
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